Methods of using IL-31 to treat chronic obstructive pulmonary disease (COPD)

ABSTRACT

Use of IL-31 agonists, including IL-31, are used to treat agonists are used to treat asthma, airway hyper-responsiveness or allergic rhinitis. The method comprise inhibiting, reducing, limiting or minimizing production of proinflammatory cytokines and include administration of the IL-31 agonist during sensitization or challenge resulting in the asthma, airway hyper-responsiveness or allergic rhinitis state.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser. No. 12/869,421, filed Aug. 26, 2010, now U.S. Pat. No. 8,029,775, which is a divisional of U.S. application Ser. No. 11/972,596, filed Jan. 10, 2008, now U.S. Pat. No. 7,799,323, and claims the benefit of U.S. Provisional Application Ser. No. 60/884,379, filed Jan. 10, 2007, all of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

Asthma is a chronic lung disease that affects more than 17 million Americans. Asthma is characterized by inflammation of the airways with intermittent bronchospasm., which is caused by the inflammation of the muscles surrounding the air passageways. Breathing may be so labored that an asthma attack becomes life-threatening. Asthma is a chronic disease and it requires continuous management and appropriate treatment.

Symptoms of asthma include cough, chest tightness, shortness of breath, and wheezing. Asthma can be triggered by a variety of irritations, such as allergens, tobacco smoke, strong odors, respiratory infections, weather changes, viral or sinus infections, exercise, stress, reflux disease (Stomach acid flowing back up the esophagus, or food pipe), medications, foods, and emotional anxiety.

Different classifications of asthma include: allergic asthma, caused by airway inflammation when exposed to allergens; exercised-induced asthma, where the airways narrow when triggered by vigorous activity; cough-variant asthma, a chronic, persistent cough without shortness of breath; and occupational asthma, which is related to working in a particular occupational environment.

Management of asthma involves several approaches, including preventing chronic and troublesome symptoms; maintaining “normal” breathing; maintain normal activity levels, including exercise; preventing recurrent asthma flare-ups, and minimize the need for emergency room visits or hospitalizations, and providing optimal medication therapy with no or minimal adverse effects. Asthma management includes using proper medications, or combinations of medications to prevent and control asthma symptoms and to reduce airway inflammation. Asthma medications are thus categorized into two general classes, quick-relief and long-term control medications. Quick-relief medications that are used to provide temporary relief of symptoms include bronchodilators, such as beta-agonists and anticholinergics, and corticosteroids. Long-term control medications are taken daily to control the airway inflammation in persistent asthma. This class includes inhaled corticosteroids to inhibit or prevent inflammation.

Thus, there is a need for additional treatment options in managing asthma and airway hyper-responsiveness. The present invention provides the use of a cytokine to aid in management of this disease.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 a shows quantitative RT-PCR analysis of IL-31RA and OSMR levels in lung tissue following sensitization with OVA and challenge with either OVA or PBS in BALB/c or C57B1/6 mice.

FIG. 1 b shows quantitative RT-PCR analysis of IL-31RA and OSMR levels in cells from bronchial alveolar lavage fluid (BAL) following sensitization with OVA and challenge with either OVA or PBS in BALB/c or C57B1/6 mice.

DESCRIPTION OF THE INVENTION

The present invention is based in part upon the discovery that mice in a model of airway hyper-responsiveness (AHR) that were treated with IL-31 indicated exhibited less AHR compared to vehicle treated controls and that IL-31 treatment decreases disease pathogenesis in a murine model of allergic asthma, possibly through the down-regulation of IL-5 and IL-13. In addition, the invention teaches the unexpected findings that timing of the administration of IL-31 and dosage are important in using IL-31 to treat asthma and ARR. Thus the present invention encompasses the use of IL-31 to treat asthma, acute respiratory distress, chronic obstructive pulmonary disease, allergic rhinitis, and respiratory diseases.

IL-31 is the HUGO name for a cytokine that has been previously described as Zcyto17rlig in a published U.S. patent application (See published U.S. patent application number 20030224487, U.S. patent application Ser. No. 10/352,554, filed Jan. 21, 2003, now issued U.S. Pat. No. 7,064,186; Sprecher, Cindy et al., 2003, incorporated herein by reference). The heterodimeric receptor for IL-31 comprises a heterodimer formed between IL-31 Ra and OncostatinM receptor beta (OSMRb). IL-31Ra is the HUGO name for a protein called zcytor17 in commonly-owned U.S. published patent application number 20030215838, U.S. patent application Ser. No. 10/351,157, filed Jan. 21, 2003, herein incorporated by reference. The polynucleotide and polypeptide sequences for human IL-31 are shown in SEQ ID NOs: 1 and 2, respectively. The polynucleotide and polypeptide sequences for murine IL-31 are shown in SEQ ID NOs: 3 and 4, respectively. As used herein the term, IL-31 shall mean zcytor17 lig as used in U.S. patent publication number 20030224487, as shown above. IL-31Ra has been previously described in commonly-owned U.S. patent application Ser. No. 09/892,949 filed Jun. 26, 2001, which is herein incorporated by reference.

Cysteine mutanst of IL-31 are described in U.S. Patent Publication 2006-0228329, published Oct. 12, 2006 and are also incorporated herein by reference. Molecules of the mature human IL-31 polypeptide can have disulfide bonds between the cysteine residues of the mature polypeptide amino acid sequence A mutation of any of these three cysteines results in a mutant form of the human IL-31 protein that will only form one disulfide bond. The cysteines in these positions can be mutated, for example, to a serine, alanine, threonine, valine, or asparagine.

The amino acid sequence for the OSMR, and IL-31RA receptors indicated that the encoded receptors belonged to the Class I cytokine receptor subfamily that includes, but is not limited to, the receptors for IL-2, IL-4, IL-7, Lif, IL-15, EPO, TPO, GM-CSF and G-CSF (for a review see, Cosman, “The Hematopoietin Receptor Superfamily” in Cytokine 5(2): 95-106, 1993). The zcytor17 receptor is fully described in commonly-owned PCT Patent Application No. US01/20484 (WIPO publication No. WO 02/00721; herein incorporated by reference).

The present invention includes the use of IL-31 molecules, including agonists, variants and fragments, having IL-31 activity to treat asthma and/or AHR. The invention includes administering to a subject the IL-31 molecule and contemplates both human and veterinary therapeutic uses. Illustrative veterinary subjects include mammalian subjects, such as farm animals and domestic animals.

The native polynucleotide and polypeptide sequences for the “long” form of IL-31RA are shown in SEQ ID NOs: 5 and 6, respectively. The native polynucleotide and polypeptide sequences for the “short” form of IL-31RA are shown in SEQ ID NOs: 7 and 8, respectively. Additional truncated forms of IL-31RA polypeptide appear to be naturally expressed. Both forms encode soluble IL-31RA receptors. The “long” soluble IL-31RA polynucleotide and polypeptide sequences are shown in SEQ ID NOs: 9 and 10, respectively. The “short” soluble IL-31RA polynucleotide and polypeptide sequences are shown in SEQ ID NOs: 11 and 12, respectively. The native polynucleotide and polypeptide sequences for mouse IL-31RA are shown in SEQ ID NOs: 13 and 14, respectively. The native polynucleotide and polypeptide sequences for human OSMRbeta are shown in SEQ ID NOs: 15 and 16, respectively. See PCT applications WO 02/00721 and WO 04/003140, both of which are incorporated by reference.

In allergic asthma, inhalation of allergens leads to an inflammatory cascade in which CD4+ T lymphocytes are thought to play a central role. The key contributions of CD4+ T cells in the pathogenesis of asthma have been highlighted by studies of Th2-type cytokines, such as IL-4, IL5, IL-9 and IL-13. These cytokines can mediate upregulation of adhesion molecules and inflammatory chemokine production, and thereby immune-cell recruitment, degranulation of eosinophils, synthesis of IgE, and hyper-reactivity of smooth muscle (reviewed 1). IL-4 and IL-13 are structurally related molecules that share the common IL-4Rα chain in receptor complexes. See Lin J. et al., Immunity 2:331-9, 1995; Smerz-Bertling C., and Duschl A., J. Biol. Chem. 270:966-70, 1995; and Zurawski S. et al., J. Biol. Chem. 270:13869-78, 1995. Although they exhibit overlapping function and both are associated with allergic disease, studies in IL-4 deficient animals have demonstrated that IL-13 may be especially critical for the induction of ABR. See Grunig G. et al., Science 282:2261-3, 1998; Herrick C. et al., J. Immunol. 170:2488-95, 2003; and Wills-Karp M. et al., Science 282:2258-61, 1998. IL-5 is central to eosinophil maturation, differentiation, activation and survival. The development of airway eosinophilia is associated with increased IL-5 expression in the airway mucosa and elevated concentrations of IL-5 in the luminal fluid and serum (Liu L. et al., J. Allergy Clin. Immunol.:106:1063-9, 2000; and Kelly E. et al., Am. J. Respir. Crit. Care Med. 156:1421-8, 1997). Additionally, studies in mice have indicated the role of IL-5 in eosinophilia through depletion in murine models of asthma (Saito H. et al., J. Immunol. 168:3017-23, 2002; Tanaka H. et al., Am. J. Respir. Cell Mol. Biol. 19:19, 2004; and Tomaki M. et al., Pulm. Pharmacol. Ther. 15:161-8, 2002). Therefore Th2 mediated cytokines play an important role in generating the inflammation that characterizes allergic diseases.

IL-31 has been found to be produced more predominantly by activated Th2 cells compared to Th1-skewed cells (Dillon et al., 2004). Subsequent analysis of lung tissue from mice exposed to a model of allergen-induced asthma showed an upregulation of the receptor for IL-31, IL-31RA, suggesting a possible association of IL-31 with allergy. In that study, RNA was isolated from human IL-31 treated A549 cells, IL-31 treated SK-LU-1 cells, and untreated control cells using a RNeasy Midi Kit (Qiagen, Valencia, Calif.) according to the manufactures instructions. Gene expression profiling of the cells treated with IL-31 and the respective control cells was carried out using GEArray Q series cDNA expression arrays (SuperArray Inc., Bethesda, Md.). The Q Series cDNA expression arrays contain up to 96 cDNA fragments associated with a specific biological pathway, or genes with similar functions or structural features. Comparison of arrays from treated and control cells allows for a determination of the up and down regulation of specific genes. Probe labeling, hybridization and detection were carried out according to the manufactures instructions. Chemiluminscent signal detection and data acquisition was carried out on a Lumi-Imager workstation (Roche, Indianapolis, Ind.). The resulting image data was analyzed using ImageQuant 5.2 (Amersham Biosciences, Inc., Piscataway, N.J.) and GEArray Analyzer 1.2 (SuperArray Inc., Bethesda, Md.) software. Analysis of the results from the Human Interleukin and Receptor Q series HS-014N arrays, showed, after normalization, an approximate 4.7 fold increase of IL13RA2 signal in the IL-31 treated human SK-LU-1 cells and an approximate 2.2 fold increase of the IL13RA2 signal in the IL-31 treated human A549 cells. These results indicate that IL-31 significantly up regulated IL13RA2 in the SK-LU-1 and A549 cells. Both of these are established cell lines derived from human lung carcinomas (Blobel et al., Virchows Arch B Cell Pathol Incl Mol. Pathol., 1984; 45(4):407-29). More specifically, A549 is characterized as a human pulmonary epithelial cell line (Lin, et al., J Pharm Pharmacol., 2002 September; 54(9):1271-8; Martinez et al., Toxicol Sci., 2002 October; 69(2):409-23).

Interleukin-13 (IL13), a cytokine secreted by activated T lymphocytes, has been demonstrated to be both necessary and sufficient for the expression of allergic asthma and for use in experimental models of asthma, which include airway hyper responsiveness, eosinophil recruitment, and mucus overproduction (Wills-Karp et al., Science, 1998; 282:2258-2261). It has been shown, that selective neutralization of IL13 will ameliorate the asthma phenotype (Grunig et al., Science, 1998; 282:2261-2263). It has also been reported that IL13 is involved in the up regulation of mucin gene MUC8 expression in human nasal polyp epithelium and cultured nasal epithelium (Kimm et al., Acta Otolaryngol., 2002; September;122(6):638-643; Seong et al., Acta Otolaryngol., 2002; June;122(4):401-407). MUC8, a major airway mucin glycoprotein, is implicated as playing a role in the pathogenesis of mucus hypersecretion in chronic sinusitis with polps (Seong et al., Acta Otolaryngol., 2002; June;122(4): 401-407).

Functionally, IL13 signals through a receptor complex consisting of the interleukin-13 receptor alpha-1 chain (IL13RA1) and IL-4 receptor alpha (IL4RA) (Daines and Hershey, J Biol. Chem., 2002; 22(12):10387-10393). It has also been shown, that the interleukin-13 receptor alpha-2 (IL13RA2) binds IL13 with high affinity, but by itself (Daines and Hershey, J Biol. Chem., 2002; 22(12):10387-10393). This receptor lacks, however, the cytoplasmic domain necessary for signaling and, therefore, is considered to be a decoy receptor. It has been shown that IL13RA2 is predominately an intracellular molecule that can be quickly mobilized from intracellular stores and surface expressed following cellular treatment with interferon (IFN)-gamma. The surface expression of IL13RA2 after IFN-gamma treatment does not involve protein synthesis and results in diminished IL13 signaling (Daines and Hershey, J Biol. Chem., 2002; 22(12):10387-10393).

The results of the gene expression array analysis for IL-31 indicate the action of IL-31 to be novel to that of IFN-gamma in that the IL-31 treatment of lung epithelial derived cell lines resulted in a significant increase of IL13RA2 gene expression. Thus, IL-31 treatment can be beneficial in cases where long-term up regulation of IL13RA2 expression and down regulation of IL13 is desired such as in asthma, airway hyperactivity (AHR), and mucin regulation, including chronic sinusitis with polyps.

The bioactive antagonists or antibody conjugates described herein can be delivered intravenously, intraarterially or intraductally, subcutaneously, topically, or may be introduced locally at the intended site of action.

Within an aspect, the invention provides a method of treating asthma, airway hyper-responsiveness, allergic rhinitis, and chronic obstructive pulmonary disease (COPD) comprising administering an IL-31 agonist to a mammal. Within an embodiment the IL-31 agonist is selected from the group consisting of: a) a polypeptide of at least 70% sequence identity to the polypeptide of SEQ ID NO: 2 from residue 27 to residue 164; b) a polypeptide comprising the sequence of SEQ ID NO: 2 from residue 27 to residue 164; c) analogues of b); d) derivatives of b); e) variants of b): and f) fragments of b). Within an embodiment the inflammation is inhibited, minimized, prevented or neutralized.

The invention provides a method of treating asthma, airway hyper-responsiveness, allergic rhinitis, comprising administering an IL-31 agonist to a mammal. In an embodiment, the IL-31 agonist is selected from the group consisting of: a) a polypeptide of at least 90% sequence identity to the polypeptide of SEQ ID NO: 2 from residue 27 to residue 164; and b) a polypeptide comprising the sequence of SEQ ID NO: 2 from residue 27 to residue 164. In an embodiment, inflammation is inhibited, minimized, or neutralized. Within an embodiment the IL-31 agonist is produced in mammalian cells. In another embodiment the IL-31 agonist is produced in E. coli. In an embodiment, the cysteine residues of the amino acid sequence of the IL-31 agonist are mutated to produce homogenous preparations of IL-31.

Within an aspect the invention provides a method of treating asthma, airway hyper-responsiveness, allergic rhinitis, comprising administering an IL-31 agonist to a mammal wherein the IL-31 agonist is administered during sensitization or challenge. Within an embodiment the IL-31 agonist is not administered as a pre-treatment to the asthma, airway hyper-responsiveness or allergic rhinitis. Within an embodiment production of proinflammatory cytokines in the lung and BAL fluid is inhibited, minimized, or neutralized. In an embodiment the proinflammatory cytokines are IL-5 or IL-13. In an embodiment the proinflammatory cytokines are IL-5 and IL-13.

Within an aspect the invention provides a method of inhibiting, minimizing, or neutralizing the production of proinflammatory cytokines in the lung and BAL fluid in a pulmonary inflammatory condition, comprising administering a polypeptide wherein the polypeptide is selected from the group consisting of: a) a polypeptide of comprising at least 90% sequence identity to the polypeptide of SEQ ID NO: 2 from residue 27 to residue 164; and b) a polypeptide comprising the sequence of SEQ ID NO: 2 from residue 27 to residue 164. In an embodiment, the polypeptide is produced in mammalian cells. In another aspect the polypeptide is produced in E. coli.

The invention provides a method for optimizing the dose of an IL-31 agonist used to treat asthma, airway hyper-responsiveness, or allergic rhinitis comprising determining the amount of the IL-31 agonist that produces a decrease in proinflammatory cytokines. In an embodiment, the proinflammatory cytokines are IL-5 or IL-13. In an aspect the proinflammatory cytokines are IL-5 and IL-13.

The invention provides a use of a pharmaceutical composition comprising an IL-31 agonist to treat, minimize, reduce or inhibit the symptoms of asthma, airway hyper-responsiveness or allergic rhinitis wherein the pharmaceutical composition is selected from the group consisting of: a) a polypeptide of comprising at least 90% sequence identity to the polypeptide of SEQ ID NO: 2 from residue 27 to residue 164; b) a polypeptide comprising amino acid residues 27 to 164 of SEQ ID NO: 2.

The invention provides a kit for determining the optimum dose for treating asthma, airway hyper-responsiveness or allergic rhinitis comprising: a) taking a sample of lung tissue or BAL fluid from a patient with asthma, airway hyper-responsiveness or allergic rhinitis; b) testing the sample in vitro to determine if an amount of an IL-31 agonist decreases proinflammatory cytokine production in the sample, wherein the amount of the proinflammatory cytokine is measured by determining the level of gene expression or protein; c) determining the dosage of the IL-31 agonist sufficient to reduce levels of the proinflammatory cytokine.

The invention provides a method of down-regulating the expression of IL-31Ra in a condition such as asthma, airway hyper-responsiveness or allergic rhinitis comprising administering an amount of an IL-31 agonist. In an embodiment, the IL-31 agonist is selected from the group consisting of: a) a polypeptide of at least 90% sequence identity to the polypeptide of SEQ ID NO: 2 from residue 27 to residue 164; and b) a polypeptide comprising the sequence of SEQ ID NO: 2 from residue 27 to residue 164. In an embodiment, inflammation is inhibited, minimized, or neutralized. In an embodiment., the IL-31 agonist is produced in mammalian cells. In another embodiment, the IL-31 agonist is produced in E. coli. In an embodiment the cysteine residues of the amino acid sequence of the IL-31 agonist are mutated to produce homogenous preparations of IL-31.

The invention is further illustrated by the following non-limiting examples.

EXAMPLES Example 1 Analysis of IL-31 in Airway Hyper-Responsiveness Murine Model

A) Sensitization and Airway Challenge

Female BALB/c and C57B1/6 mice 6 weeks of age were purchased from Charles River Laboratories and maintained under SPF conditions. Groups of mice 8 to 10 wks of age, were sensitized by intraperitoneal injection of 10 ug of OVA (Calbiochem) in 50% Imject Alum (Pierce) on days 0 and 7. Seven days later, mice were challenged on 2 consecutive days (days 14 and 15) with 20 ug of OVA in 50 ul PBS. Forty-eight hours following allergen challenge whole lung tissue, BAL cellular infiltrates, BAL fluid and serum from half the sensitized animals were collected for further analysis while the remaining mice were assessed for airway hyper responsiveness (AHR).

B) Bronchoalveolar Lavage

Bronchoalveolar lavage fluid was collected via intratracheal cannulation. Saline was slowly injected in the lung and withdrawn in 4×1 ml aliquots. The lavage fluids were centrifuged to isolate the BAL cells and the supernatant was frozen for later analysis. BAL cell pellets were resuspended at 2 million cells per ml and 150 ul was used for total and differential cell counts. Total BAL leukocyte counts were determined for each mouse via light microscopy using trypan blue exclusion. Differential cell counts in the lavage fluid of each animal were determined by H&E staining (DiffQuik; Merz & Dade, Dubingen, Switzerland) of air-dried and fixed cytospin slides. Cell counts were calculated by examining one hundred cells per cytospin (Phoenix Laboratories). The total number of different leukocytes was calculated from the data collection. Results are expressed as number of cells per lung.

C) Measurement of Airway Hyper-Responsiveness

Airway responsiveness was assessed as a change in airway function following challenge with aerosolized methacholine (MCh) using whole-body plethysmography (Buxco, Electronics, Shannon, Conn.) 14. Briefly, unrestrained, conscious mice were placed in a whole-body plethysmographic chamber and respiratory waveforms were measured for 5 min to obtain a basal line. After basal values were established, mice were challenged with aerosolized saline for the unchallenged control measurement and then increasing concentrations of MCh (0.075M to 0.3 M). Readings were taken over a 10 min period 3 min after each nebulization period. Data are expressed as fold increase above basal values using the dimensionless parameter PehnH.

D) RNA Isolation and Real-time TaqMan PCR Analysis

Lung tissue and BAL cells were collected from animals 48 h following antigen challenge. Snap frozen whole tissue samples and BAL cell pellets, resuspended in RLT buffer, were stored at −80° C. until processed for RNA isolation. Briefly, lung tissue was homogenized in RLT buffer (Qiagen) and extracted using the commercially available RNeasy kits as per the manufacturer's instructions (Qiagen, Valencia, Calif.). The RNA was transcribed into first strand cDNA using Taqman RT-PCR reagents (Applied Biosystems, Branchburk, N.J.), according to the manufacturer's protocol. Levels of murine IL-31, IL-31RA, IL-4, IFNg, TNFa, CD40, CD40L, Class II, Cathepsin L, IL-13Ra2, MIP-2, IL-8R, Eotaxin and OSMR mRNA were determined via multiplex real-time TaqMan PCR. Oligonucleotide primers and TaqMan probes were designed using the Primer Express software (PE Applied Biosystems, Foster City, Calif.) and were synthesized in house. Forward primer, reverse primer and probe sequences were generated. Levels of mRNA for each gene were calculated relative to the internal house-keeping gene, hypoxanthine-guanine-phosphoribosyl-transferase (HPRT) using the Comparative Ct method (User Bulletin #2, PE Applied Biosystems).

E) BAL Fluid and Serum Cytokine Analysis

Cytokine levels in BAL fluid supernatants and serum samples were measured using the Mouse Cytokine LINCOplex kit (LINCO Research, St Charles, Miss.) and the Luminex100 plate reader (Luminex Corporation, Austin, Tex.) according to the manufacturer's instructions. Quantification of cytokines was performed by regression analysis from a standard curve generated from cytokine standards included in the kit. Lower limits of detection for IL-5 and IL-13 were 0.6 pg/ml and 4.7 pg/ml respectively.

F) IL-31 Administration by Osmotic Pump

Mouse IL-31 was delivered at a dose of 20 ug per day (approximately 1 mg/kg per day) for 14 days by an osmotic minipump (Alzet) implanted subcutaneously into the dorsum of BALB/c mice. PBS+0.1% BSA was included as the vehicle control. Pumps were implanted on day 3 to ensure IL-31 delivery throughout the course of the model.

G) Histopathology of Murine Lung

Lungs were fixed by inflation and immersion in 10% normal buffered formalin (NBF).

Immunohistochemistry of Human Lung

5 uM sections were incubated with primary antibodies diluted from 333 ng/ml to 1330 ng/ml for both IL31 and IL31RA for 60 min in ChemMate Antibody Dilution Buffer (part# ADB250, Ventana Medical systems). Tissues were washed twice in TBST, and then incubated for 45 min in biotinylated goat anti-rabbit Ab, 750 ng/ml in PBSB (catalog #BA-1000, Vector Labs). Slides were washed and incubated in Vectastain Elite ABC Reagent (catalog# PK-7100, Vector Labs) for 45 min and washed twice in TBST. Signals were developed with DAB+(catalog# K-3468, DakoCytomation) for 10 min at room temperature. Tissue slides were then counterstained in hematoxylin (catalog# H-3401 Vector Labs), dehydrated and coverslipped in VectorMount (catalog# H-5000, Vector Labs).

Statistical Analysis

Analysis of variance (ANOVA) was used to determine the levels of difference between groups for BAL differentials, and serum IgE. Student's t test was performed to determine differences between groups for gene expression studies. The data are expressed as mean±SD. Differences were considered statistically significant when p<0.05.

Results:

Systemic delivery with IL-31 during a mouse model of allergic asthma results in decreased levels of IL-5 and IL-13 mRNA and protein. Preliminary analysis of lung tissue and BAL cellular infiltrates from animals in a mouse model of antigen-induced asthma showed that mRNA encoding IL-31RA, the receptor for IL-31, was up-regulated in both whole lung tissue and lung cellular infiltrates 48 h after airway antigen challenge (Dillon et al., 2004).

Purified IL-31 was delivered at 20 ug/day for 14 days during the course of the allergen-induced asthma model via subcutaneous insertion of a mini-osmotic pump. Forty-eight hours following allergen inhalation of sensitized mice we collected whole lung tissue, BAL cellular infiltrates, BAL fluid and serum. RNA isolated from lung tissue and BAL cells were analyzed via quantitative TaqMan PCR for expression of 16 genes, including IL-31RA, IL-31, IL-4, IL-5, IL-13, IFNg, TNFa, CD40, CD40L, Class II, Cathepsin L, IL-13Ra2, MIP-2, IL-8R, Eotaxin, and OSMR. Results from these studies showed significant down-regulation of IL-5 (p 0.013), IL-13 (p 0.003) and Cathepsin L (p 0.038) mRNA in whole lung tissue, and decreases in IL-4 (p 0.01), IL-5 (p 0.003), IL-13 (p<0.001), Cathepsin L (p 0.007), Class II (p 0.005), CD40 (p 0.011), and CD40L (p<0.001) in BAL cell mRNA from allergen sensitized and challenged animals treated with IL-31 compared to vehicle control treated animals. Analysis of BAL fluid for cytokines confirmed the down-regulation of both IL-5 and IL-13 (p<0.001). In addition, IL-31 treatment resulted in lower levels of IL-5 in the serum. Serum IL-13 could not be detected in either the control or IL-31-treated animals.

IL-31 treatment results in decreased lung inflammation and airway hyper-responsiveness following allergen sensitization and challenge. The classic triad of allergic asthma involves IgE production, airway hyper-responsiveness (AHR) and eosinophilic inflammation. AHR is a well-established characteristic of allergic asthma and is believed to be the result of airway mucosal inflammation. Clinical investigations have suggested a relationship between the presence of activated airway inflammatory cells, including T cells, mast cells, monocytes, eosinophils and neutrophils, morphologic changes in airway tissues, and the development of severity of AHR (See Bradley B., et al., J. Allergy Clin. Immuno1.88:661-74, 1991; and Wardlaw A. et al., Am. Rev. Respir. Dis. 137:62-9, 1998). Analysis of airway infiltrating cells following allergen sensitization and challenge in the presence of daily IL-31 treatment resulted in significant decreases in lymphocytes (p 0.001), macrophages (p0.029) and eosinophils (p 0.019) in BAL fluid. Histological analysis of formalin fixed lung tissue indicated that inflammatory cell infiltrates and goblet cell hyperplasia in lungs from mice treated with IL-31 were substantially less than vehicle controls, suggesting a beneficial effect of IL-31 in airway inflammation.

Analysis of AHR of IL-31-treated animals via whole body plethysmography indicated that mice treated with IL-31 exhibited less AHR compared to vehicle treated controls. No change was apparent in serum IgE levels between IL-31- or vehicle-treated mice. These data therefore indicate that IL-31 treatment decreases disease pathogenesis in a murine model of allergic asthma, possibly through the down-regulation of IL-5 and IL-13.

IL-31RA is expressed in human alveolar macrophages, type II pneumocytes and bronchiolar epithelium. Immunohistochemical (IHC) analysis of IL-31RA expression in human asthmatic lung and normal tissues indicates IL-31RA is present on alveolar macrophages, type II pneumocytes (an epithelial derived cell type that is responsible for secretion of surfactant) and bronchiolar epithelium. Comparison between asthmatic lung and normal lung tissue showed no difference in the cellular staining pattern.

Example 2 Human Monocyte Staining

Whole blood (200 ml) was collected from a healthy human donor and mixed 1:1 with PBS in 50 ml conical tubes. Thirty ml of diluted blood was then underlayed with 15 ml of Ficoll Paque Plus (Amersham Pharmacia Biotech, Uppsala, Sweden). These gradients were centrifuged 30 min at 500 g and allowed to stop without braking. The RBC-depleted cells at the interface (PBMC) were collected and washed 3 times with PBS. The isolated human PBMC yield was 300×10⁶ prior to selection described below.

The PBMCs were suspended in 3 ml MACS buffer (PBS, 0.5% BSA, 2 mM EDTA) and 1×10⁶ cells were set aside for flow cytometric analysis. We next added 0.45 ml anti-human CD14 microbeads (Miltenyi Biotec) and the mixture was incubated for 20 min at 4 degrees C. These cells labeled with CD14 beads were washed with 30 ml MACS buffer, and then resuspended in 1.5 ml MACS buffer.

An LS column (Miltenyi) was prepared according to the manufacturer's instructions. The LS column was then placed in a MidiMACS magnetic field (Miltenyi). The column was equilibrated with 3 ml MACS buffer. The cells labeled with anti-human CD14 microbeads were then applied to the column. The CD14-negative cells were allowed to pass through. The column was rinsed with 10 ml (2×5 ml) MACS buffer and the rinse was pooled with the CD14-negative flow-through cells. The column was then removed from the magnet and placed in a 15 ml falcon tube. CD14-positive cells were eluted by adding 5 ml MACS buffer twice to the column and bound cells flushed out using the plunger provided by the manufacturer. The yield of CD14+ selected human peripheral blood monocytes was 30×10⁶ total cells. One million of these monocytes were set aside for flow cytometric analysis. The CD14-negative flow-through cells were counted and 1×10⁶ cells were set aside for flow cytometric analysis.

The 1×10⁶ PBMCs, CD14-positive and CD14-negative cells that had been set aside were stained and run on a fluorescence activated cell sorter (FACS) to assess the purity of the CD14+ selected human peripheral blood cells. A FITC-conjugated anti-human CD19 antibody, an anti-human CD56-PE Ab, an anti-human CD11b-CyChrome Ab, and an anti-human CD3-APC Ab (all from PharMingen) were used for staining the cells. The CD14+ selected cells were 88% CD14+. The PBMCs were 10% CD14+ and the CD14-negative cells were 0.1% CD14+.

The human CD14+ selected human peripheral blood monocytes were activated by incubating them at 2×106 cells/ml in RPMI+10% human ultraserum (Gemini Bioproducts, Calabasas, Calif.) with and without rhInterferon-gamma (IFNg) 10 ng/ml (R&D) for 4, 8, 12 or 24 hours at 37° C. in ultra low-attachment tissue culture plates (Corning/Costar). At each timepoint, the cells were harvested, pelleted, washed once with FACS stain buffer (PBS, 3% human ultraserum, 1% BSA, 10 mM HEPES) and counted.

The activated monocytes were stained by FACS as follows: 1×10⁶ cells were combined with specific and non-specific antibody blocking reagents-soluble receptor IL-31RaCEE and zVen1CEE respectively—at 200 ug/ml or none. The cells were then combined with either 2.0 μg/mL of biotinylated mouse anti-human IL-31Ra or biotinylated mouse isotype negative control (Southern Biotechnology) or left unstained for 30 minutes on ice in FACS buffer. Cells were washed twice with FACS buffer and then stained with SA-PE (Jackson Immuno Laboratories) at 1:400 in combination with FITC-conjugated anti-human CD14 antibody at 1:100 (PharMingen) for 20 minutes on ice. Cells were then washed twice with FACS buffer and resuspended in 400 ul FACS buffer containing 7-aminoactinomycin D (Molecular Probes) at 1:800 and analyzed by FACS on a BD FACSCaliber using CellQuest software (Becton Dickinson, Mountain View, Calif.).

The biotinylation of mouse-anti-human IL-31 Ra was done as follows: 205 μL of mouse anti-human IL-31Ra (clone#276.100.5.5) at 2.45 mg/mL was combined with 15 μL of 2 mg/mL EZ-link Sulfo-NHS-LC-biotin (Pierce, Rockford, Ill.) dissolved in ddH2O. This solution was incubated on a rocker for 30 minutes at room temperature. After biotinylation the solution was purified on a PD-10 column (Amersham Biosciences, Uppsala, Sweden).

Human CD14+ selected human peripheral blood monocytes activated with rhIFNg for 12 h and 24 h showed binding to the biotinylated mouse anti-human IL-31 Ra reagent+SA-PE. The binding was most pronounced at the 12 h timepoint. This binding did not occur in cells initially combined with specific competitor protein IL-31. There was no staining with SA-PE alone or with the biotinylated mouse isotype negative control+SA-PE. No binding was observed with the biotinylated mouse anti-human IL-31 Ra reagent+SA-PE on CD14+ selected human peripheral blood monocytes activated with rhIFNg for 4 h and 8 h.

Example 3 Effects of IL-31 on Allergen Induced Airway Hyper-Responsiveness

3.1 Materials and Methods

3.1.1 Mice.

Female BALB/c mice were purchased from Charles River Laboratories and maintained under SPF conditions. All experimental animals used were under a protocol approved by the Institutional Animal Care and Use Committee (IACUC) of ZymoGenetics. Mice were 11 weeks of age at onset of study.

Tg mice over-expressing murine IL31, driven by the lymphocyte-specific promoter/enhancer Eμ/1ck, or the ubiquitous promoter EF1α were used to evaluate the effects of IL-31 in vivo. The serum of EF1 μTg mice contained 0.3-1.1 ng/ml mIL-31, while the Eμ/1ck Tg serum contained 10-43 ng/ml. Both types of IL-31 Tg mice develop a striking skin phenotype around 4-8 weeks of age, consisting of piloerection followed by mild to severe alopecia. The Tg skin is also highly pruritic, as evidenced by the scratching behavior of the mice, often excessive enough to induce excoriation and lesions of the skin.

3.1.2 Sensitization and Airway Challenge.

Mice between the age of 8 and 12 weeks were sensitized by 100 □L intraperitoneal injection of 10 ug of OVA (Calbiochem) in 50% Imject Alum (Pierce) on days 0 and 7. One week later, mice were challenged intranasally on two consecutive days (days 14 and 15) with 20 □g of OVA in 50 uL PBS. Forty-eight hours following intranasal challenge with OVA, whole lung tissue, bronchoalveolar lavage (BAL) cellular infiltrates, BAL fluid and serum were collected from animals. In some experiments, an extra group of animals were put on protocol and tested for airway hyper-responsiveness (AHR) by whole body plethysmography (WBP).

3.1.3 IL-31 Administration by Osmotic Pump.

Murine IL-31 was delivered for either 7 or 14 days by an osmotic mini-pump (Alzet) implanted subcutaneously into the dorsum of BALB/c mice. PBS+0.1% BSA was included as the vehicle control. The quantity of IL-31 delivered is outlined below. In general, delivery of IL-31 with a 14 day pump ensured that IL-31 was present in the circulation during both the allergen sensitization and challenges phases. The majority of experiments were performed with E. coli-derived IL-31 (SEQ ID NO: 17), however BHK-derived material (SEQ ID NO: 2) was shown to have a similar effect.

3.1.4 Measurement of Airway Hyper-Responsiveness.

Airway responsiveness was assessed as a change in airway function following challenge with aerosolized methacholine (MCh) using whole-body plethysmography (Buxco, Electronics, Shannon, Conn.). Briefly, unrestrained, conscious mice were placed in a whole-body plethysmographic chamber and respiratory waveforms were measured for 5 min to obtain a basal line. After basal values were established, mice were challenged with aerosolized PBS for the unchallenged control measurement and then increasing concentrations of MCh (0.075M to 0.3 M). Readings were taken over a 10 min period 3 min after each nebulization period. Data are expressed as fold increase above basal values using the dimensionless parameter Penh (enhanced pause).

3.1.5 Bronchoalveolar Lavage.

Bronchoalveolar lavage fluid was collected via intratracheal cannulation. PBS with 0.5% FBS was slowly injected in the lung and withdrawn in 3×1 ml aliquots. The lavage fluids were centrifuged to isolate the BAL cells and the supernatant was frozen for later analysis. BAL cell pellets were resuspended at 2 million cells per ml and 150□L was used for total and differential cell counts. Total BAL leukocyte counts were determined for each mouse via light microscopy using trypan blue exclusion. Differential cell counts in the lavage fluid of each animal were determined by H&E staining (DiffQuik; Merz & Dade, Dubingen, Switzerland) of air-dried and fixed cytospin slides. Cell counts were calculated by examining one hundred cells per cytospin (Phoenix Laboratories). The total number of different leukocytes was calculated from the data collection. Results are expressed number of total cells per lung.

3.1.6 RNA Isolation and Real-Time Taqman PCR Analysis.

Lung tissue and BAL cells were collected from animals 48 h following antigen challenge. Lung tissues from animals were analyzed separately, whereas BAL cells from animals within a group were pooled, due to the small amount of material. Snap frozen whole tissue samples and BAL cell pellets, resuspended in RLT buffer, were stored at −80° C. until processed for RNA isolation. Briefly, lung tissue was homogenized in RLT buffer (Qiagen) and extracted using the commercially available RNeasy kits as per the manufacturer's instructions (Qiagen, Valencia, Calif.). The RNA was transcribed into first strand cDNA using TaqMan RT-PCR reagents (Applied Biosystems, Branchburk, N.J.), according to the manufacturer's protocol. Oligonucleotide primers and TaqMan probes were designed using the Primer Express software (PE Applied Biosystems, Foster City, Calif.) and were synthesized in house. Forward primer, reverse primer and probe sequences were prepared. Real-time PCR were run in triplicate in 384-well plates on ABI Prism 7900HT (Applied Biosystems). Real-time data were acquired and analyzed using SDS 2.0 software (Applied Biosystems) with manual adjustment of baseline and threshold parameters. Levels of mRNA for each gene were calculated relative to the internal housekeeping gene, hypoxanthine-guanine-phosphoribosyl-transferase (HPRT) using the Comparative Ct method (User Bulletin #2, PE Applied Biosystems).

3.1.7 BAL Fluid Cytokine Analysis.

Cytokine levels in BAL fluid supernatants and serum samples were measured using a custom Mouse Cytokine LINCOplex kit (LINCO Research, St Charles, Miss.) and the Luminex100 plate reader (Luminex Corporation, Austin, Tex.) according to the manufacturer's instructions. Quantification of cytokines was performed by regression analysis from a standard curve generated from cytokine standards included in the kit.

3.1.8 Quantification of Serum IgE.

Serum levels of total IgE and OVA-specific IgE were measured by ELISA. ELISA microtiter plates (Nunc Maxisorb) were coated overnight with 100 ul/well of 2 ug/ml capture anti-IgE (Pharmingen cat#553413) in PBS at 4° C. Plates were then blocked with 200 ul/well SuperBlock (Pierce cat#37515) for 15 minutes RT, then washed with ELISA C. Diluted IgE standards (Pharmingen cat#557079) in ELISA B (PBS, 1% BSA) were plated serial 2 fold dilutions from 500 ng/ml. Serum samples diluted 1:50 in ELISA B were plated 100 ul/well. If measuring Ova-specific IgE concentrations, sera from mice that have been immunized and boosted with ova/alum was used as a positive reference and serum from naïve mice as a negative reference. Reference sera were diluted 1:50, same as sample sera. Plates were incubated overnight at 4° C. and then washed with ELISA C. Biotinylated detection anti-mouse IgE (Pharmingen cat#553419) at 2 ug/ml in ELISA B was then plated 100 ul/well, and incubated 60 minutes at RT. Washed plates in ELISA C, and then plated 100 ul/well of SA-HRP (Pharmingen cat#554066) diluted 1:1000 in ELISA B, and incubated 30 minutes at RT. After incubation, plates were washed with ELISA C, then developed using OPD (10 ml NaCitrate/citris acid pH5, 1 OPD tablet (Pierce, Cat#34006), 10 ul H2O2). Stopped development of ELISA plate with 0.1M H2SO4, and read on spectrophotometer at 490 nm.

Results

3.2.1 Expression of IL-31RA in Murine Airways

3.2.1.1 Regulation of IL-31RA and OSMR mRNA

In initial studies of OVA sensitized and challenged mice, mRNA from lung tissues and cells from BAL were analyzed for expression of IL-31 receptor to determine the potential for IL-31 activity in allergen-induced airway inflammation. BALB/c and C57B1/6 mice were sensitized with OVA, then challenged intranasally with either OVA as the allergen or PBS as the control. Quantitative RT-PCR analysis of tissues suggested that IL-31Ra was significantly up-regulated in both lung tissue (FIG. 1) and in BAL cell infiltrates following allergen-challenge in sensitized mice. OSMR, the other subunit of the IL-31 receptor, was also found to be expressed in the lung, though expression did not appear to be regulated as a result of allergen sensitization. In contrast, in BAL cells OSMR levels were very low. These data suggest that IL-31 signaling may play a role in the development of airway inflammation following allergen sensitization.

3.2.1.2 IL-31RA Protein Expression

To determine where IL-31RA protein was expressed in murine lungs, we collected lungs from animals that had been sensitized with OVA and challenged intranasally with either OVA or PBS. We then analyzed expression of IL-31RA by immunohistochemistry and found that the major cell type expressing IL-31 appeared to be macrophages. We also noted staining in large monocytic cells that may represent resident monocytes. This was especially appreciated in the lung from PBS treated animals in which minimal inflammatory infiltrate was observed. It was also noted that the occasional positive staining macrophage was observed in the alveoli of these latter, “uninvolved” lungs.

3.2.2 Delivery of IL-31 in OVA-Induced Airway Hyper-Responsiveness

3.2.2.1 Experiment #1

To follow the observation that IL-31Ra was regulated during antigen-induced airway inflammation in mice, we studied the effect of IL-31 delivery on the development of airway inflammation. To this end, OVA-specific airway inflammation was generated in the presence or absence of circulating murine IL-31 in BALB/c animals. Briefly, BALB/c mice were sensitized intraperitoneally with 10 ug of OVA in Alum on day 0 and day 7. On day 3, five of the sensitized animals were implanted subcutaneously with an osmotic mini-pump that delivered murine IL-31 (BHK-derived) for 14 days at 20 ug of IL-31 per day (approximately 1 mg/kg per day). This rate of delivery resulted in approximately 20 ng/ml of IL-31 in the serum. Another group of five animals were implanted with pumps containing PBS+0.1% BSA as the vehicle control. Animals were then challenged intranasally on day 14 and 15 with OVA. A third group of animals were sensitized with OVA but challenged with PBS and were included as a baseline control (no inflammation). Forty-eight hours after the last intranasal challenge, tissues were collected for analysis. Lungs were lavaged for analysis of BAL cell infiltrates and mRNA was prepared from BAL cell infiltrates as well as whole lung homogenates for analysis of gene regulation. Serum was collected for analysis of cytokines and IgE levels.

3.2.2.1.1 Lung and BAL mRNA Analysis

Analysis of gene expression in lung with IL-31 delivery suggests that IL-31 can significantly decrease expression of genes that have been shown to be involved in the development of asthma and pulmonary inflammation, including IL-5, IL13 and Cathepsin L (p value 0.0137, 0.003 and 0.0381, respectively, BSA-treatment versus IL-31-treatment) (Table 1). There was also a trend towards decreases in the expression of IL-4, IL-31Ra, TNFa, CD40 and CD40L, though the results did not reach statistical significance. Interestingly, there was a significant increase in IL-8R gene expression following IL-31-treatment compared to vehicle-control animals and a trend towards increases in MIP-2, though this was not significant. MIP-2, and KC, are functional homologues of IL-8 in mice. MIP-2 and KC increase the functional activity of neutrophils including ingestion and killing of bacteria. The implications of these findings for IL-8Rand MIP-2 are unclear but it is known that IL-8R is expressed on neutrophils and is required for neutrophil chemotaxis.

TABLE 1 mRNA Levels in Total Lung Homogenates from Vehicle- and IL-31-Treated Mice ^(a)Lung Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.081 + 0.041 0.038 + 0.006 0.001 + 0.000 NS (p = 0.0535) IL-5 0.756 + 0.192 0.407 + 0.157 0.097 + 0.040 p = 0.0137 IL-13 0.236 + 0.043 0.099 + 0.026 0.002 + 0.001 p = 0.003 IL-31Ra 1.276 + 0.597 0.605 + 0.332 0.053 + 0.008 NS (p = 0.0591) TNFa 0.566 + 0.160 0.073 + 0.041 0.057 + 0.054 NS MIP-2 0.623 + 0.439  1.36 + 0.666 0.410 + 0.201 NS IL-8R 3.148 + 0.452 7.998 + 4.20  3.595 + 0.489 p = 0.0334 BCL-6 4.645 + 0.487 4.962 + 0.632 2.409 + 0.279 NS CCL27 0.566 + 0.139 0.760 + 0.139 0.659 + 0.361 NS CCR10 0.418 + 0.052 0.569 + 0.388 0.444 + 0.027 NS TSLP 1.844 + 0.344 1.982 + 0.310 1.844 + 1.029 NS Cathepsin L 198.8 + 72.61 113.8 + 24.44 30.63 + 8.145 p = 0.0381 Class II 23.10 + 7.489 18.02 + 8.432 10.73 + 1.605 NS CCL17 8.219 + 2.029 9.857 + 3.746 1.667 + 0.210 NS IL-13Ra 0.604 + 0.468 0.568 + 0.833 0.004 + 0.002 NS Eotaxin-1 15.43 + 2.221 16.09 + 1.072 1.246 + 0.134 NS IL-10 0.182 + 0.049 0.179 + 0.045 0.016 + 0.009 NS CD40 8.469 + 2.745 5.830 + 1.366 3.501 + 0.294 NS CD40L 0.747 + 0.241 0.493 + 0.123 0.479 + 0.054 NS ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS groups represent baseline values when animals have not challenged with OVA.

Analysis of gene expression in cells within the BAL showed genes that were similarly regulated to the lung tissues. IL-4, IL-5, IL-13, IL-31Ra, Cathepsin L, Class II, CCL17, IL-10, CD40, CD40L were all significantly down-regulated in mRNA from BAL cells pooled from animals within each group. Of note, IL-8R and MIP-2 showed a trend towards increased expression in the BAL cells, but the results were not statistically significant (Table 2).

TABLE 2 mRNA Levels in BAL Cell Homogenates from BSA- and IL-31-Treated Mice BAL Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.056 + 0.017 0.010 + 0.001 ND p = 0.0101 IL-5 0.090 + 0.015 0.027 + 0.008 0.018 + 0.012 p = 0.0032 IL-13 0.080 + 0.006 0.018 + 0.003 ND p < 0.0001 IL-31Ra  2.28 + 0.179  1.41 + 0.227 0.008 + 0.006 p = 0.0066 TNFa 0.469 + 0.073 0.542 + 0.035 2.166 + 0.249 NS MIP-2 3.782 ± 0.312 4.605 ± 0.488 3.335 + 0.221 NS IL-8R 1.459 + 0.304  1.709 + 0.1244 0.161 + 0.037 NS BCL-6 1.983 + 0.694  0.652 + 0.0462 0.459 + 0.014 p = 0.0295 CCL27 0.103 + 0.048 0.058 + 0.015 0.025 + 0.006 NS CCR10 0.202 + 0.039 0.270 + 0.048 0.198 + 0.051 NS TSLP 0.043 + 0.031 0.076 + 0.031 0.040 + 0.047 NS Cathepsin L 731.3 + 69.52 426.5 + 80.06 42.60 + 4.661 p = 0.0076 Class II 18.43 + 4.192 5.070 + 0.598 2.759 + 0.151 p = 0.0054 CCL17 10.89 + 1.584 8.236 + 0.306 0.347 + 0.048 p = 0.0462 IL-13Ra 0.039 + 0.017 0.013 + 0.004 ND NS Eotaxin-1 0.073 + 0.017 0.055 + 0.017 0.018 + 0.013 NS IL-10 0.326 + 0.046 0.130 + 0.019 0.009 + 0.008 p = 0.0024 CD40 0.493 + 0.116 0.190 + 0.022 0.045 + 0.015 p = 0.0122 CD40L 0.780 + 0.028 0.214 + 0.100 0.060 + 0.012 p = 0.0007 ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS groups represent baseline values when animals have not challenged with OVA.

3.2.2.1.2 Serum Cytokines and IgE Levels

Analysis of serum cytokines showed significant decreases in circulating levels of IL-5 protein between vehicle-treated (110+15.7 pg/ml) and IL-31-treated mice (37+8.4 pg/ml) (p<0.0001). Although IL-6, IL-9, IL-10, IL-12, GM-CSF, MIP-1 and RANTES were detected, no differences were observed between treatment groups. IL-4 and IL-13 protein could not be detected in the serum of mice in this experiment.

No significant difference in circulating total IgE or OVA-specific IgE was noted between the two groups of animals.

3.2.2.1.3 BAL Differentials

Analysis of cellular differentials in the BAL showed significant decreases in the number of total lymphocytes in the BAL of IL-31-treated mice compared to vehicle-treated animals (p 0.0095) and a trend towards decreases in BAL eosinophils, though the differences were not statistically significant. The increased IL-8R mRNA expression in the lung and BAL tissues suggested there may be an increase in neutrophils in the BAL. Although there was a trend towards increased neutrophil numbers following IL-31-treatment, the results were not statistically significant due to the large variation within the groups and the small number of cells. It should also be noted that 48 hr is the optimal time-point for measurement of macrophage and eosinophil influx, not neutrophil infiltration. Analysis of earlier time-points for more precise assessment of neutrophil infiltration may be warranted.

3.2.2.2 Experiment #2

A repeat of Experiment #1 analyzing antigen-specific airway hyper-responsiveness, was performed in the presence or absence of circulating murine IL-31 in BALB/c animals.

3.2.2.2.1 Lung and BAL mRNA Levels

Only a subset of genes was analyzed in this experiment compared to Experiment #1. These genes included IL-4, IL-5, IL-13, IL-13Ra2, IL31RA, Cathepsin L and TNFa. A complete summary of levels of gene expression relative to the house-keeping control gene, HPRT are given in Table 3. In this experiment, significant decreases in gene expression for IL-13 and TNFa were observed for mice treated with IL-31 compared to vehicle control animals. Although there was a trend towards decreases in IL-5, IL-31RA and Cathepsin L mRNA, three genes which showed significant decreases in the first experiment, the differences between treatment groups were not statistically significant in this experiment. The results for the BAL mRNA are shown in Table 4 and show that similar genes to the first experiment were significantly down-regulated in this experiment upon IL-31-treatment. These genes include significant down-regulation of IL-5, IL-31RA and Cathepsin L. IL-13 levels were also significantly down-regulated but the levels of IL-13 mRNA detected for this analysis were at the lower limit of detection.

TABLE 3 mRNA Levels in Total Lung Homogenates from BSA- and IL-31-Treated Mice ^(a)Lung ^(b)Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.502 + 0.278 0.360 + 0.089 0.010 + 0.009 NS IL-5 1.345 + 0.480 0.807 + 0.347 0.204 + 0.06  NS (p = 0.0772) IL-13 0.084 + 0.046 0.033 + 0.017 ND p = 0.0492 IL-31Ra 2.178 + 0.607 1.849 + 0.691 0.211 + 0.066 NS TNFa 2.028 + 0.427 1.355 + 0.435 1.749 + 0.924 p = 0.0388 Cathepsin L 534.7 + 208.8 349.2 + 81.03 240.1 + 19.82 NS IL-13Ra2 1.043 + 0.342 0.940 + 0.424 0.024 + 0.001 NS ^(a)Data are represented as mean + standard deviation of five animals per group. ^(b)Statistical analysis was performed using a unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS groups represent baseline values when animals have not challenged with OVA. NS = not significant, ND = not detected

TABLE 4 mRNA Levels in BAL Cell Homogenates from BSA- and IL-31-Treated Mice ^(a)BAL ^(b)Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.064 + 0.029 0.056 + 0.003 ND NS IL-5 0.106 + 0.006 0.048 + 0.001 ND p < 0.0001 IL-13 0.009 + 0.001 0.002 + 0.001 ND p = 0.0007 IL-31Ra 2.198 + 0.189 1.536 + 0.180 0.006 + 0.002 p = 0.0118 TNFa 1.138 + 0.281 2.047 + 0.836 2.546 + 0.278 NS Cathepsin L 424.9 + 93.04 150.9 + 20.04 31.61 + 2.99  p = 0.0076 IL-13Ra2 0.033 + 0.010 0.027 + 0.011 ND NS ^(a)Data are represented as mean + standard deviation of five animals per group. ^(b)Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS groups represent baseline values when animals have not challenged with OVA. NS = not significant, ND = not detected

3.2.2.2.2 BAL Fluid Cytokines

Results of the analysis of cytokines in the BAL fluid are summarized in Table 5. Consistent with results for regulation of mRNA in the lung and BAL cells, analysis of protein levels in the BAL fluid show significant decreases in IL-5 (p<0.0001) and IL-13 (p<0.0001). In addition, significant increases in KC (p 0.0332) and MCP-1 (p 0.007) were observed in mice treated with IL-31. Although KC mRNA expression was not tested in this experiment, the previous experiment had shown evidence for KC up-regulation following IL-31 treatment. The detection of protein in the BAL fluid supports the finding that IL-31-treatment up-regulates KC levels in the lung. Levels of GM-CSF, IFN-g, IL-10, IL-12, IL-1b, IL-4, IL-6, IL-9 and RANTES were undetectable. MIP-1a and TNFa were detected but no difference were observed between IL-31-treated and untreated animals (Table 5).

TABLE 5 Cytokine Levels in BAL Fluid from BSA- and IL-31-Treated Mice ^(a)BAL Fluid Cytokines Vehicle v IL-31 Cytokine Vehicle-Treated IL-31-Treated p Value IL-13 18.61 + 1.93  5.23 + 1.30 p < 0.0001 IL-5 39.37 + 2.59 15.62 + 2.60 p < 0.0001 KC 22.81 + 1.63 40.59 + 7.32 p = 0.0032 MCP-1  3.11 + 1.72 10.46 + 1.89 p = 0.007 MIP-1a  6.11 + 0.59  7.17 + 1.68 NS TNFa  1.11 + 1.20  1.70 + 1.15 NS ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS groups represent baseline values when animals have not challenged with OVA.

3.2.2.2.3 Serum Cytokines and IgE Levels

Analysis of serum cytokines suggested no statistically significant decreases in circulating levels of any of the cytokines detected including IL-5, IL-6, IL-9, IL-10, IL-12, IL-13, GM-CSF, MIP-1a and TNFa. IL-4 and RANTES protein could not be detected in the serum of mice in this experiment.

No statistically significant difference in circulating total IgE or OVA-specific IgE was noted between the two groups of animals.

3.2.2.2.4 BAL Differentials

Differential analysis of cells in the BAL suggested, similar to the findings in the first experiment, that IL-31 treatment resulted in a significant decrease in infiltrating eosinophils and a trend towards decreases in lymphocytes, though in this case, the differences for lymphocytes were not statistically significant. In this experiment, the observed increase in neutrophils with IL-31 treatment compared to vehicle control animals did reach significance only when tested in a unpaired t-tailed t-test (p=0.0203), and is consistent with the finding of increased KC in the BAL fluid. However, statistical analysis using a two-way ANOVA, to analyze all data and all parameters together, suggested that the differences in neutrophils between the two groups was not statistically significant.

3.2.2.3 Experiment #3

Similarly to the previous two experiments, analysis of antigen-specific airway hyper-responsiveness was performed in the presence or absence of circulating murine IL-31M BALB/c animals.

3.2.2.3.1 Lung and BAL mRNA Levels

A complete summary of levels of gene expression relative to the house-keeping control gene, HPRT are given in Table 5. The significant decreases observed in IL-4, IL-5, IL-13 and IL-31Ra gene expression in mice treated with IL-31 compared to vehicle controls is consistent with the previous two experiments (Table 6). As seen in Experiment #1, there was also a trend towards increases in IL-8R gene expression in the IL-31-treated group compared to vehicle-treated mice however the differences were not statistically significant.

The results for the BAL mRNA are shown in Table 6 and reflect the results found for the lung. IL-31-treatment induces significant down-regulation of IL-4, IL-5, IL-13, and IL-31RA and increases in IL-8R mRNA expression in the BAL cells (Table 7).

TABLE 6 mRNA Levels in Total Lung Homogenates from Vehicle- and IL-31-Treated Mice ^(a)Lung Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.402 + 0.081 0.259 + 0.069 0.004 + 0.001 p = 0.0266 IL-5 1.677 + 0.521 0.617 + 0.081 0.172 + 0.022 p = 0.0054 IL-13 0.483 + 0.205 0.036 + 0.047 ND p = 0.0040 IL-31Ra 6.306 + 2.055 2.132 + 1.341 0.274 + 0.044 p = 0.0102 CCL17 44.18 + 18.62 55.13 + 26.47 4.72 + 1.89 NS IL-8R 56.59 + 18.81 130.13 + 83.79  177.1 + 46.82 NS (p = 0.0942) IL-13Ra2 1.145 + 0.304 0.779 + 0.343 0.013 + 0.006 NS ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals.

TABLE 7 mRNA Levels in BAL Cell Homogenates from BSA- and IL-31-Treated Mice ^(a)BAL Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.426 + 0.021 0.344 + 0.015 ND p = 0.0055 IL-5 0.573 + 0.176 0.188 + 0.019 0.009 + 0.004 p = 0.0195 IL-13 0.243 + 0.084 0.002 + 0.001 ND p = 0.0076 IL-31Ra 18.89 + 5.21  7.496 + 1.629 0.079 + 0.011 p = 0.0224 CCL17 84.89 + 7.725 99.12 + 9.007 4.557 + 0.266 NS IL-8R 39.35 + 9.557 105.32 + 10.78  17.31 + 3.713 p = 0.0014 IL-13Ra2 0.143 + 0.064 0.193 + 0.090 0.005 + 0.008 NS ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals.

3.2.2.3.2 BAL Fluid Cytokines

Results of the analysis of cytokines in the BAL fluid are summarized in Table 8. Similarly to the previous data, these data show significant decreases in IL-5 (p=0.0133) and IL-13 (p<0.0001) with IL-31 Treatment. However, in contrast to the previous experiments, analysis of KC and MCP-1 in the BAL showed decreased levels in IL31-treated mice compared to vehicle control animals (p=0.0405 and p=0.0387, respectively) (Table 8). IL-1b, IL-10, MIP-1a and RANTES levels were below the limit of detection of the assay.

TABLE 8 Cytokine Levels in BAL Fluid from BSA- and IL-31-Treated Mice ^(a)BAL Fluid Cytokines Vehicle v IL-31 Cytokine Vehicle-Treated IL-31-Treated p Value IL-2 1.816 + 0.695 1.938 + 0.621 NS IL-4  3.19 + 0.627 3.891 + 3.339 NS IL-5 80.38 + 21.96 47.49 + 18.11 p = 0.0133 IL-6 2.104 + 1.478 2.658 + 1.531 NS IL-9 47.47 + 14.79 36.33 + 4.002 NS IL-12 12.76 + 2.038 13.25 + 2.976 NS IL-13 46.42 + 5.140 25.10 + 3.843 p < 0.0001 IFNg 5.238 + 1.750 6.349 + 2.310 NS TNFa 8.026 + 1.882 8.126 + 2.874 NS GM-CSF 26.27 + 5.496 29.72 + 4.761 NS MCP-1 19.79 + 3.025 16.89 + 1.481 p = 0.0387 KC 15.43 + 5.737 9.969 + 2.819 p = 0.0405 ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals.

3.2.2.3.3 Serum Analysis

No significant difference in circulating total IgE or OVA-specific IgE was noted between the two groups of animals. Serum cytokines were not measured

3.2.2.3.4 BAL Differentials

Differential analysis of cells in the BAL suggested that IL-31 treatment resulted in a significant decrease in infiltrating lymphocytes (p=0.0011), macrophages (p=0.0291) and eosinophils (p=0.0198), as has been observed in previous experiment. There was no statistical difference in the number of neutrophils found in BAL of mice in the two treatment groups.

3.2.2.4 Experiment #4

In order to determine the overall effect of IL-31 treatment on airway inflammation, this study was designed to include the collection of lung tissue for immunohistochemistry and to analyze the airway hyper-responsiveness of live mice to allergen challenge by WBP. The mice were sensitized and challenged with OVA and treated with IL-31 (E. coli-derived) or vehicle as previously described in the last three experiments. Forty-eight hours the after the last intranasal challenge, tissue was collected for analysis as before. In addition, a portion of the lung was collected and preserved in 10% buffered neutral formalin or in Zn TRIS fixative. The formalin fixed tissue was processed, embedded in paraffin, sectioned and the resulting slides stained with hematoxylin and eosin for microscopic evaluation.

3.2.2.4.1 Lung and BAL mRNA Levels

A complete summary of levels of gene expression relative to the house-keeping control gene, HPRT are given in Table 9. As expected, a significant decrease in IL-5 and IL-31Ra gene expression was observed in mice treated with IL-31 compared to vehicle-treated controls (Table 9). There was a trend towards decreases in IL-4, IL-13 and Cathepsin L and significant decreases in IFNg and CD40L, which has been observed previously. In addition, we once again observe a statistically significant increase in IL-8R expression in total lung homogenates (Table 9).

The gene expression levels in BAL cell infiltrates are summarized in Table 10 and indicate, similar to previous studies, that IL-31-treatment induces significant down-regulation of most of genes tested including IL-4, IL-5, IL-13 and Cathepsin L. There was a trend towards decreasing IL-31Ra expression, though not statistically significant. In this particular analysis we found a significant increase is MIP-2 and TNFa, both of which have shown trends towards an increase in BAL cell mRNA from previous experiments (i.e. Experiment #1 and/or Experiment #2). IL-8R was also significantly increased in BAL mRNA, suggesting a disassociation between regulation of genes in the BAL cells and total lung.

TABLE 9 Levels in Total Lung Homogenates from Vehicle- and IL-31-Treated Mice ^(a)Lung Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.042 + 0.027  0.02 + 0.014 0.001 + 0.000 NS IL-5 0.298 + 0.056 0.097 + 0.048 0.029 + 0.010 p = 0.0016 IL-13 0.068 + 0.070 0.023 + 0.016 ND NS IL-31Ra 0.713 + 0.129 0.352 + 0.263 0.047 + 0.015 p = 0.0484 TNFa 0.245 + 0.094 0.167 + 0.031 0.342 + 0.121 NS MIP-2 0.570 + 0.194 0.482 + 0.174 0.398 + 0.238 NS IL-8R 1.369 + 0.672 10.85 + 6.129 6.162 + 1.876 p = 0.0337 IFNg 0.135 + 0.019 0.069 + 0.034 0.033 + 0.008 p = 0.0153 CCL27 0.359 + 0.162 0.637 + 0.028 0.662 + 0.073 p = 0.0146 Cathepsin L 86.49 + 39.68 37.90 + 33.67 18.59 + 1.48  NS (p = 0.0670) Class II 23.73 + 9.840 17.25 + 6.162 7.195 + 0.347 NS IL-13Ra ND ND ND ND Eotaxin 5.696 + 2.416 5.073 + 3.232 0.317 + 0.057 NS IL-10 0.145 + 0.086 0.112 + 0.076 0.005 + 0.003 NS CD40 3.343 + 0.559 2.562 + 0.832 1.835 + 0.138 NS CD40L 0.576 + 0.165 0.301 + 0.137 0.183 + 0.071 p = 0.0426 ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS group represents baseline with no OVA challenge.

TABLE 10 mRNA Levels in BAL Cell Homogenates from Vehicle- and IL-31-Treated Mice ^(a)BAL Vehicle v IL-31 Gene Vehicle-Treated IL-31-Treated PBS p Value IL-4 0.0867 + 0.005  0.011 + 0.002 ND p < 0.0001 IL-5 0.188 + 0.005 0.054 + 0.013 ND p < 0.0001 IL-13 0.0352 + 0.001  0.0026 + 0.001  ND p < 0.0001 IL-31Ra 1.719 + 0.760 0.671 + 0.202 0.011 + 0.007 NS TNFa 0.293 + 0.045 0.582 + 0.085  5.38 + 0.404 p = 0.0065 MIP-2 0.334 + 0.045 1.108 + 0.254  9.20 + 0.134 p = 0.0065 IL-8R  1.99 + 0.139 0.616 + 0.023  1.33 + 0.095 p < 0.0001 IFNg 0.196 + 0.011 0.0681 + 0.006  0.003 + 0.001 p < 0.0001 CCL27 0.094 + 0.006 0.057 + 0.02  0.030 + 0.003 p = 0.0385 Cathepsin L 851.6 + 40.64 284.5 + 20.8  46.07 + 10.03 p < 0.0001 Class II 27.69 + 3.34   5.41 + 0.476 1.265 + 0.043 p = 0.0003 Eotaxin 0.011 + 0.003 ND ND ND IL-10 0.466 + 0.051 0.075 + 0.008 0.004 + 0.001 p = 0.002 CD40 0.771 + 0.033 0.079 + 0.010 0.024 + 0.002 P < 0.0001 CD40L 0.711 + 0.012 0.234 + 0.013 0.016 + 0.004 p < 0.0001 ^(a)Data are represented as mean + standard deviation of five animals per group. Statistical analysis was performed using an unpaired t-test comparing vehicle-treated groups with IL-31 treated animals. The PBS group represents baseline with no OVA challenge.

3.2.2.4.2 Serum

Serum was analyzed for total and antigen-specific IgE in IL-31-treated and vehicle-treated OVA-sensitized mice. In this particular experiment we found a significant decrease in the level of OVA-specific IgE in IL-31 treated mice compared to vehicle-treated animals (p=0.0070). However, the differences in total IgE levels between the two treatment groups did not reach statistical significance.

Serum cytokines and cytokine levels in the BAL fluid were not analyzed in this experiment.

3.2.2.4.3 Lung Histology

Histological examination of the lungs from IL-31 treated and vehicle treated animals showed a number of microscopic changes associated with sensitization and challenge with OVA, including: 1) multifocal to diffuse peribronchial/perivascular subacute inflammation that was characterized by accumulations of eosinophils and/or neutrophils (segmented nucleus with eosinophilic cytoplasm) and large monocytic type cells along with some lymphocytes; 2) diffuse epithelial/goblet cell hyperplasia; and 3) multifocal macrophage infiltrate in the alveoli with some multinucleated giant cell formation.

In some areas of the lung, there was evidence of perivascular edema with or without variable amounts of inflammatory infiltrates as well as evidence of interstitial fibrosis. When compared with the lungs from vehicle-treated animals that were sensitized and challenged with OVA, the inflammatory changes in the IL-31-treated animals were substantially less severe suggesting a beneficial effect of IL-31. Representative images of lung from vehicle-treated and IL-31-treated animals are shown in.

The lung sections from vehicle-treated animals showing severe inflammation also showed an increased number of F4/80+ macrophage infiltrating the alveoli, peribronchial and perivascular subacute inflammatory area. Lung sections from IL-31-treated animal showed less inflammation and also showed significant lower number of F4/80+ macrophage infiltrate. Enumeration of F4/80+ macrophages showed that the F4/80+ cell density was significantly lower in IL31-treated animals compared to BSA-treated mice (p=0.0154, Unpaired-T test).

OVA-sensitized animals were challenged intranasally and measured for airway hyper-responsiveness by whole body plethysmography. Analysis of the dimensionless parameter enhanced pause (PenH) following challenge with increasing concentration of methacholine suggested that IL-31-treated animals were less sensitive to allergen challenge compared to vehicle-treated mice. This data support the histopathology findings and suggest that IL-31 treatment decreases airway inflammation to allergen.

BAL cell differentials were not performed in this experiment

3.2.2.5 Summary

The data presented suggest that IL-31 delivery during antigen sensitization and airway challenge in mice results in down-regulation of pulmonary inflammation, as assessed by histology and airway hyper-responsiveness via whole body plethysmography. Analysis of gene regulation in total lung homogenates and in mRNA from infiltrating cells in the lung suggest that IL-31 can consistently down-regulate genes that have been associated with pulmonary inflammation and asthma including, IL-5, IL-13 and Cathepsin L. Genes generally associated with inflammation were also found to be down-regulated and include IFNg, CD40 and CD40L. The IL-31 effect on gene down-regulation appeared to be more consistent in mRNA from BAL infiltrating cells compared to total lung mRNA. Moreover, when cytokine levels in the BAL fluid were tested, concordant down-regulation of protein was often observed. This down-regulation of Th2 and inflammatory genes often translated to decreases in BAL cell infiltrates, particularly eosinophils, macrophages and lymphocytes. Analysis of F4/80+ macrophage cell numbers in lungs of IL-31-treated animals via histomorphometry yielded quantitative data that confirmed the decrease in tissue macrophages in the lung. Furthermore, analysis of general pathology associated with pulmonary allergic inflammation showed decreases in severity of disease with delivery of IL-31. These data therefore suggest that delivery of IL-31 during allergen sensitization and challenge can reduce the severity of pulmonary inflammation through an as yet unknown mechanism.

3.2.3 Dose Response to IL-31

2.3.1 Experiment #1

We next decided to investigate the minimum dose of IL-31 required for the inhibitory effects on pulmonary inflammation following OVA sensitization and intranasal challenge in mice. In the first experiment, Alzet 14-day osmotic pumps were loaded with 10-fold decreasing concentrations of IL-31, from 20 ug/day to 0.02 ug/day, and implanted in mice during OVA allergen sensitization and challenge as previously described. Five animals per group were analyzed.

3.2.3.1.1 Lung and BAL Cell mRNA

Previous studies have shown that delivering 20 ug/day of IL-31 decreases expression of a number of genes in the lung following allergen sensitization and challenge. Results summarized in Table 11 show that for some of these genes, this effect of IL-31 is dose-dependant. Comparison of gene expression levels in the group of mice treated with 20 ug/day of IL-31 with those receiving 10-, 100- or 1000-fold less IL-31 shows significant differences. Genes including, IL-5, IL-13, IL-31Ra, TNFa, IFNg, Class II, IL-13Ra2, Eotaxin, IL-10, CD40 and CD40L, were more highly expressed at lower doses of IL-31, especially at the 0.2 and 0.02 ug/day doses. Cathepsin L and IL-4 showed trends towards increased expression with lower doses of IL-31, but these trends were not significant. Furthermore, IL-8R and MIP-2, which have been shown to be increased following 20 ug/day IL-31-treatment, also showed significant IL-31-dose dependency.

TABLE 11 mRNA Analysis of Lungs from IL-31-Treated Mice ^(a)IL-31 Concentration in pump Gene ^(b)20 ug/day 2 ug/day 0.2 ug/day 0.02 ug/day IL-4 0.025 + 0.017 0.047 + 0.025 0.041 + 0.006  0.042 + 0.005 IL-5 0.094 + 0.033 0.195 + 0.115  0.292 + 0.131**  0.251 + 0.035* IL-13 0.012 + 0.007  0.057 + 0.030* 0.036 + 0.016   0.077 + 0.041** IL-31Ra 0.294 + 0.157 0.543 + 0.208 0.826 + 0.312*  0.988 + 0.287** TNFa 0.340 + 0.082 0.370 + 0.088 0.432 + 0.0804  0.656 + 0.204** MIP-2 12.25 + 9.78  4.942 + 4.497 6.436 + 1.050  4.555 + 2.648 IL-8R 6.943 + 2.740 5.498 + 2.103 3.236 + 1.412*  3.477 + 0.914* IFNg 0.084 + 0.026 0.150 + 0.052 0.279 + 0.154* 0.229 + 0.125 CCL27 1.114 + 0.184  0.834 + 0.130* 0.993 + 0.152  0.914 + 0.129 Cathepsin L 49.32 + 12.92 68.84 + 14.57 98.11 + 49.52  78.10 + 31.41 Class II 30.70 + 7.802 41.56 + 7.701 50.62 + 8.797*  52.79 + 31.41** IL-13Ra2 0.068 + 0.044 0.095 + 0.035 0.116 + 0.026   0.172 + 0.032** Eotaxin 7.820 + 3.676  13.69 + 2.827** 9.327 + 1.638   12.10 + 1.613* IL-10 0.057 + 0.032  0.110 + 0.018* 0.105 + 0.011*  0.108 + 0.039* CD40 5.606 + 1.180 5.616 + 1.180  9.194 + 1.910** 6.772 + 2.000 CD40L 0.734 + 0.335 0.790 + 0.182 1.899 + 1.343* 1.308 + 0.169 ^(a)Data a presented as mean + standard deviation of five animals per group. ^(b)**p < 0.01 and *p < 0.05 using one-way ANOVA with Dunnett's post test, comparing IL-31-treatment at lower concentrations (2, 0.2 and 0.02 ug/day) to treatment the standard 20 ug/day used in previous experiments.

TABLE 12 mRNA Levels in BAL Cell Homogenates from Dose curve IL-31-Treated Mice ^(a)IL-31 Concentration in pump (ug/day) Gene ^(b)20 ug/day 2 ug/day 0.2 ug/day 0.02 ug/day IL-4 0.039 + 0.009 0.031 + 0.007  0.055 + 0.009  0.049 + 0.005  IL-5 0.016 + 0.002 0.034 + 0.003*  0.080 + 0.010** 0.082 + 0.006** IL-13 0.001 + 0.000 0.005 + 0.000** 0.023_0.001** 0.015 + 0.000** IL-31Ra 0.850 + 0.250 1.286 + 0.079*  1.605 + 0.129** 1.420 + 0.100** TNFa 0.446 + 0.013 0.351 + 0.034*  0.282 + 0.039** 0.342 + 0.030** MIP-2 5.041 + 1.058 4.983 + 0.582  1.771 + 0.212** 1.304 + 0.095** IL-8R 4.269 + 0.308 2.244 + 0.246** 2.678 + 0.138** 3.114 + 0.202** IFNg 0.072 + 0.012 0.162 + 0.020** 0.242 + 0.019** 0.288 + 0.040** Cathepsin L 109.0 + 15.09 75.35 + 5.911** 172.8 + 30.58  103.1 + 6.720  Class II 2.148 + 0.142 4.676 + 0.407** 9.186 + 0.519** 10.24 + 1.293** IL-13Ra2 ND ND ND ND IL-10 0.055 + 0.004 0.084 + 0.007*  0.124 + 0.031** 0.110 + 0.002** CD40 0.066 + 0.008 0.071 + 0.006  0.124 + 0.006** 0.171 + 0.027** CD40L 0.151 + 0.027 0.107 + 0.006  0.267 + 0.090  0.215 + 0.054  ^(a)Data a presented as mean + standard deviation of five animals per group. ^(b)**p < 0.01 and *p < 0.05 using one-way ANOVA with Dunnett's post test, comparing IL-31-treatment at lower concentrations (2, 0.2 and 0.02 ug/day) to treatment the standard 20 ug/day used in previous experiments.

3.2.3.1.2 BAL Fluid Differentials

Analysis of BAL cell infiltrates also suggested that there is a dose dependant effect on the quantity and type of cellular infiltrates following intranasal challenge with allergen. Doses of IL-31 at 20 and 2 ug/day are more effective at inducing significant decreases in eosinophil, macrophage and lymphocyte numbers in the lung cell infiltrates compared to the lower doses of IL-31 (0.2 and 0.02 ug/day).

No statistical significance was observed in OVA-specific or total IgE (data not shown)

Serum, BAL fluid cytokines and airway hyper-responsiveness was not measured in this experiment.

3.2.3.2 Experiment #2

In the previous experiment, we demonstrated that the effect of IL-31 on airway inflammation was dose-dependant. Analysis of gene expression and BAL cell infiltrates suggested that a 10-fold lower dose of IL-31 (2 ug/day) was able to significantly inhibit the level of cellular infiltrate in the lung following intranasal challenge with the allergen. This experiment was designed to determine whether 2 ug/day and lower doses of IL-31 could decrease airway hyper-responsiveness following allergen sensitization and challenge.

Alzet 14-day osmotic pumps were loading with increasing concentrations of IL-31, from 0.005 ug/day to 2 ug/day, and implanted in mice during OVA allergen sensitization and challenge. Analysis was performed as previously described on 5 mice per group.

3.2.3.2.1 Lung and BAL Cell mRNA

Analysis of lung mRNA from IL-31-treated animals, to determine the lowest effective concentration of the IL-31 for down-regulation of genes in the lung, demonstrated that although some genes like IL-4,1′-13, IFNg, IL-31Ra and TNFa showed a trend towards down-regulation of expression at increasing concentrations of IL-31 (maximum dose of 2 ug/ml), the differences were not statistically significant in most genes (Table 14). CD40L was the only gene tested that showed significant down-regulation of expression when only 2 ug or 0.2 ug/day of IL-31 was delivered. The PCR data for all genes tested in lung tissues are summarized in (Table 13).

TABLE 13 mRNA Analysis of Lungs from IL-31-Treated Mice

^(a)Data a presented as mean + standard deviation of five animals per group. Statistical analysis was a one-way ANOVA with Dunnett's post test, comparing IL-31-treatment versus vehicle control (no IL-31, grey column) (**p < 0.01 and *p < 0.05).

Table 14 shows the gene analysis for cells in the BAL fluid. Trends for gene regulation in the cells of the HAL were less obvious (Table 14). Consistent with previous studies, MIP-2 and IL-8R were up-regulated at 2 ug/ml but not at lower concentrations of IL-31 (Table 14). Interestingly, there appeared to be an up-regulation of some genes at some of the concentrations of IL-31 below 2 ug/day, suggesting a possible bell curve for IL-31 activity. This was particularly obvious for IL-5 and IL-13 (Table 14). The corresponding protein levels in the BAL fluid demonstrate a consistent pattern between gene regulation and protein levels in the BAL. KC, which is related to MIP-2, was also found to be up-regulated at 2 ug/ml of IL-31.

TABLE 14 mRNA Levels in BAL Cell Homogenates from Dose curve IL-31-Treated Mice

^(a)Data are presented of mean + standard deviation of triplicate wells of pooled BAL cells collected from five animals per group. Statistical analysis was performed using one-way ANOVA with Dunnett's post test, comparing IL-31-treatment to vehicle control treated animals (no IL-31, grey column) (**p < 0.01 and *p < 0.05).

3.2.3.2.2 BAL Fluid Cytokines

BAL fluid was analyzed for cytokines by a luminex multiplex assay. IL-4, IL-5. IL-9, IL-13 and KC were all detected in the BAL fluid. The levels of cytokines in the BAL fluid appeared to reflect the data collected for expression of the genes in the BAL, with the lower concentrations of IL-31 inducing significantly higher levels of IL-5 and IL-13 protein. IL-4 also appeared to be up-regulated at the lower concentrations but the difference between IL-31 treatment and no treatment did not reach statistical significance. KC was found to be up-regulated at 2 ug/day compared to no treatment. No TNFa, IFNg and MCP-1 was detected in the BAL fluid. MIP-2 was not tested.

3.2.3.2.3 BAL Fluid Differentials

Analysis of BAL differentials shows that there was a trend towards a decrease in eosinophil infiltrates in the BAL of mice treated with the maximum concentration of IL-31 in this study (2 ug/day) compared to those mice that were treated with the lower doses. Due to the large degree of variation, the data was not statistically significant. There was a significant decrease in macrophage numbers with 2 ug/day of IL-31. None of the other IL-31 concentrations seemed to be effective at decreasing macrophage numbers.

3.2.3.2.4 Serum IgE

Past experiments have indicated that the decreases in inflammatory parameters associated with IL-31 treatment at higher concentrations (20 ug/day) generally do not result in decreases in either total IgE or OVA-specific IgE (refer to section 1 of this report). Nevertheless, serum was analyzed for total and OVA-specific IgE following treatment with different concentrations of IL-31. In this experiment, although there were no differences in the levels of total IgE in the sera of these mice, there did appear to be an increase in OVA-specific IgE in the groups that were treated with 0.02 and 0.01 ug per day of IL-31 compared to either no IL-31 treatment or the lowest dose of IL-31 (0.0054 day). It is interesting to note here that 0.1 ug/day of IL-31 induced significant up-regulation of IL-5 and IL-13 mRNA and protein in BAL fluid (Table 15). This data might suggest that although high concentrations of IL-31 decrease pulmonary inflammation to airway allergens, low concentrations of IL-31 may have the opposite effect.

3.2.3.2.5 Whole Body Plethysmography

Mice were further analyzed by whole body plethysmography for airway hyper-responsiveness following intranasal challenge with OVA. IL-31 treatment at the concentrations tested in this experiment did not decrease airway hyper-responsiveness.

3.2.3.3 Experiment #3

Our data have so far indicated that the anti-inflammatory effect of IL-31 in a murine model of airway hyper-responsiveness requires delivery of at least 20 ug/day of IL-31. A 10-fold decrease in IL-31 concentration does not consistently reduce airway inflammation and does not result in reduce airway hyper-responsiveness to allergen challenge. Immunohistochemistry of the mouse lung indicates that the majority of IL-31RA is expressed on both resident and infiltrating macrophage in the lung and it is unknown at this point if IL-31 is acting directly on these cells to produce the anti-inflammatory effect or if there is another target cell type. In order to determine if IL-31 acts on a resident cell type to down-regulate that inflammation associated with antigen-challenge and sensitization we wished to determine whether IL-31 pre-treatment (IL-31 delivery prior to sensitization and challenge) would have the same effect as IL-31 delivery throughout both the sensitization and challenge phases of the model.

Mouse IL-31 was delivered at a dose of 20 □g per day (approximately 1 mg/kg per day) by an osmotic mini-pump (Alzet) implanted subcutaneously into the dorsum of BALB/c mice. Mice were either implanted with 7-day pumps 7 days prior to the first OVA sensitization (IL-31 pre-treatment) or with 14-day pumps three days post-sensitization (IL-31 treatment) to compare treatment prior to sensitization and treatment during sensitization and challenge. As in all experiments so far, PBS+0.1% BSA was included as the vehicle control. Murine IL-31 derived from E. coli, was used to prepare IL-31 pumps.

3.2.3.3.1 Lung and BAL mRNA

Analysis of gene expression in total lung homogenates from vehicle-treated, IL-31 pre-treated and IL-31 treated mice are summarized in Table 15. Statistical analysis was performed by comparing the IL-31 groups (pre-treatment or treatment) to the vehicle control group.

The data clearly show that down-regulation of genes associated with inflammation mostly only occurs when IL-31 treatment is present throughout sensitization and challenge. Genes requiring the presence of IL-31 during the entire period of sensitization and challenge include IL-4, IL-5 and IL-31RA. A number of additional genes were down-regulated regardless of whether IL-31 was given as a pre-treatment or during sensitization and challenge. These genes include IL-9, TNFa, IFNg, Cathepsin L, IL-10, CD40 and CD40L.

Interestingly, IL-13 was found to be significantly increased compared to vehicle treated controls when IL-31 was given as a pre-treatment (Table 15). Of all the genes tested, IL-13 was the only gene that showed this pattern of expression. IL-13 has been shown to be involved in the manifestation of disease in this model.

TABLE 15 Levels in Total Lung Homogenates from Vehicle- and IL-31-Treated Mice IL-31 Pre- Gene Treatment IL-31 Treatment Vehicle Control IL-4 0.041 + 0.009 0.0270.009* 0.048 + 0.012 IL-5 0.357 + 0.074 0.242 + 0.172** 0.557 + 0.156 IL-9  0.009 + 0.007** 0.003 + 0.002** 0.112 + 0.075 IL-13  0.207 + 0.055* 0.082 + 0.038  0.100 + 0.052 IL-31Ra 1.452 + 0.433 0.612 + 0.243**  2.034 + 0.6116 TNFa  0.219 + 0.049* 0.229 + 0.083*  0.439 + 0.174 MIP-2 1.199 + 0.586 2.748 + 0.795  1.990 + 0.679 IL-8R 2.334 + 0.828 4.306 + 1.951  2.533 + 0.700 IFNg  0.158 + 0.055** 0.125 + 0.058** 0.586 + 0.263 CCL27  0.474 + 0.56** 0.687 + 0.061  0.823 + 0.170 Cathepsin  14.82 + 3.574** 13.537 + 5.252**  29.53 + 10.56 L Class II 54.04 + 9.134 45.30 + 12.71  46.16 + 6.801 IL-13Ra2 ND ND ND Eotaxin 5.060 + 1.166 4.205 + 2.007  3.648 + 0.654 IL-10  0.106 + 0.018* 0.067 + 0.027** 0.196 + 0.079 CD40  2.121 + 0.293** 1.906 + 0.319** 3.531 + 0.692 CD40L  0.773 + 0.190* 0.721 + 0.208*  1.245 + 0.421 ^(a)Data a presented as mean + standard deviation of five animals per group. **p < 0.01 and *p < 0.05 using one-way ANOVA with Dunnett's post test, comparing IL-31 pre-treatment or IL-31-treatment with vehicle control (no IL-31).

Previous studies of gene regulation in mRNA from BAL cells has shown that IL-31 treatment can prevent the up-regulation of mRNA encoding asthma related genes such as IL-5 and IL-13. In this experiment, similar results were observed for IL-31 treated animals compared to vehicle treated controls (Table 16).

Once again, IL-31 treatment, when given during sensitization and challenge, significantly down-regulated IL-5, IL-13, IL-31Ra, IFNg, Cathepsin L, Class II, CD40 and CD40L gene expression in cells collected from the BAL. In striking contrast however, IL-31 pre-treatment appears to significantly increase the expression of many of these genes when compared to vehicle control animals including IL-5, IL-13, IFNg, Class II, CD40 and CD40L.

These data suggest that IL-31 pre-treatment may have an adverse effect on pulmonary inflammation compared to vehicle control mice and may indeed exacerbate the disease. We have seen in the previous experiments that IL-31 treatment down-regulates the expression of IL-31RA in both lung and BAL cellular infiltrates. IL-31 pre-treatment may down-regulate the receptor prior to sensitization so that Th2 responses are exacerbated.

Of note, IL-31 treatment up-regulated IL-8R and MIP-2 as has been previously observed, whereas IL-31 pre-treatment had no effect.

TABLE 16 Levels in BAL mRNA Homogenates from BSA- and IL-31-Treated Mice IL-31 Pre- Gene Treatment IL-31 Treatment Vehicle Control IL-4 0.019 + 0.004 0.009 + 0.002  0.013 + 0.004 IL-5  0.127 + 0.021** 0.027 + 0.008*  0.069 + 0.019 IL-9 ND ND ND IL-13  0.139 + 0.018** 0.024 + 0.004*  0.051 + 0.009 IL-31Ra 2.569 + 0.328 0.971 + 0.139** 2.459 + 0.131 TNFA 0.260 + 0.021 0.433 + 0.041  0.274 + 0.014 MIP-2 1.563 + 0.059 4.110 + 0.231** 0.994 + 0.081 IL-8R 0.671 + 0.026 1.442 + 0.143** 0.605 + 0.100 IFNg  0.336 + 0.022** 0.118 + 0.015** 0.245 + 0.016 CCL27 0.059 + 0.009 0.045 + 0.013  0.062 + 0.021 Cathepsin 60.79 + 4.704 43.76 + 4.628** 83.75 + 20.88 L Class II  54.09 + 5.045** 10.173 + 0.608**  37.65 + 1.466 IL-13Ra2 ND ND ND Eotaxin ND ND ND IL-10 0.298 + 0.071 0.071 + 0.010** 0.221 + 0.029 CD40  0.202 + 0.023** 0.053 + 0.001** 0.137 + 0.013 CD40L  0.793 + 0.021** 0.253 + 0.009** 0.590 + 0.080 ^(a)Data are presented of mean + standard deviation of triplicate wells of pooled BAL cells collected from five animals per group. **p < 0.01 and *p < 0.05 using one-way ANOVA with Dunnett's post test, comparing IL-31 pre-treatment or IL-31-treatment to vehicle control treated animals (no IL-31)

3.2.3.3.2 BAL Fluid Cytokines

The animals receiving IL-31 treatment showed a trend towards decreases in IL-4, IL-5 and IL-13 in the BAL fluid compared to the vehicle treated group, though the results were not statistically significant. Consistent with previous studies with IL-31-treated mice, this group also had significantly elevated KC levels. All other cytokines that were assayed were below the limit of detection.

In contrast to the IL-31 treated animals, cytokine analysis of BAL fluid from mice that were pre-treated with IL-31 showed significant increases in the levels of IL-5, IL-9, and IL-13 compared to vehicle treated mice. This data is consistent with the up-regulation of genes like IL-5 and IL-13 in mRNA from BAL cells following pre-treatment with IL-31 and suggest that IL-31 pre-treatment may exacerbate pulmonary inflammation.

3.2.3.3.3 BAL Fluid Differentials

Analysis of cell differentials showed a trend towards lower eosinophil infiltrates in the BAL of mice treated with IL-31 during OVA sensitization and challenge, which is consistent with previous studies. Pre-treatment of mice with IL-31 prior to sensitization and challenge did not appear to alter the type or number of cellular infiltrates significantly from vehicle-treated control animals.

3.2.3.3.4 Serum IgE

There was no significant difference between groups in either total IgE, or OVA-specific IgE levels.

3.2.3.3.5 Whole Body Plethysmography

Groups of mice that were pre-treated with IL-31, treated with IL-31 during sensitization and challenge, or treated with vehicle were analyzed for their sensitivity to airway hyper-responsiveness following intranasal allergen challenge. Results indicate that IL-31 pre-treatment does not affect airway hyper-responsiveness compared to a no IL-31 treatment control. In contrast however, IL-31 treatment throughout sensitization and challenge decreased airway hyper-responsiveness to levels comparable to those animals that had not received an allergen challenge.

This current study indicates that IL-31 pre-treatment is unsuccessful at decreasing airway hyper-responsiveness and although pre-treatment may increase IL-5, IL-13 and IL-9 levels in the BAL fluid, this does not appear to exacerbate airway hyper-responsiveness compared to no IL-31 treatment.

3.2.3.4 Summary

We have previously established that 20 ug/day of IL-31 delivered during OVA sensitization and challenge results in down-regulation of pulmonary inflammation. In this section we demonstrate that this effect is dose-dependent. Although concentrations of IL-31 as low as 2 ug/day can still reduce expression of genes that are important in the development of airway hyper-responsiveness, this low concentration was not sufficient to result in reduced airway hyper-responsiveness as measured by whole body plethysmography.

In addition, although the receptor for IL-31 appears to be expressed on both resident and infiltrating macrophages in the lung, pre-treatment with IL-31 immediately prior to allergen sensitization is not sufficient to achieve the anti-inflammatory effects of IL-31 we have so far observed. Moreover, it is possible that IL-31 pre-treatment may increase production of Th-2-type cytokines such as IL-5, IL-13 and IL-9. This finding may be in support of a recent finding suggesting that IL-31RA regulates Th-2-type inflammatory responses and that in the absence of IL-31RA receptor Th-2-type responses may be exacerbated (3). We know that delivery of IL-31 can down-regulate IL-31RA and we postulate that pre-treatment with IL-31 results in the effective absence of IL-31RA prior to antigen sensitization resulting in increased expression of IL-5, IL-13 and IL-9. In this particular experiment however, those increases in Th-2-type cytokines did not result in exacerbated airway hyper-responsiveness.

3.2.4 Airway Hyper-Responsiveness in IL-31 Transgenics

3.2.4.1 Experiment #1

IL-31 transgenic animals were sensitized and challenged with OVA as previously described and tested for airway hyper-responsiveness by whole body plethysmography. The data suggest that IL-31 transgenic animals were significantly less sensitive to OVA-induced airway hyper-responsiveness compared to wildtype control littermates.

3.2.4.2 Experiment #2

This experiment was to repeat the test of the sensitivity of IL-31 transgenic mice to allergen induced airway hyper-responsiveness. Analysis of the data show similar findings to the previous experiment. IL-31 transgenic animals appear less susceptible to pulmonary inflammation induced by a sensitizing allergen, especially at the highest dose of methacholine.

3.2.4.3 Experiment #3

Having established that IL-31 transgenic animals appear less sensitive to airway hyper-responsiveness as measured by whole body plethysmography, we analyzed the nature of the decreased inflammation in the lungs. Therefore, IL-31 transgenic animals and wildtype controls were sensitized with OVA and challenged via the airways with either OVA or PBS. Forty-eight hours following intranasal challenge, BAL fluid was collected for assessment of lung cellular infiltrates and lung was collected for mRNA and gene expression analysis. Serum was also collected for analysis of total and OVA-specific IgE. In this experiment, cytokines in the BAL fluid and serum were not measured.

3.2.4.3.1 Lung and BAL mRNA

Lung mRNA was tested by quantitative RT-PCR for expression of a panel of genes that have been implicated in pulmonary inflammation. Two sets of comparisons were made between the four groups of animals. Table 17 shows data from the first analysis where IL-31 transgenic animals were directly compared to wildtype mice under conditions of either OVA or PBS sensitization. In general, there were no differences between IL-31 transgenic and control littermates when challenged with either OVA or PBS. For a number of genes there appeared to be lower expression in the lungs of IL-31 transgenics following OVA sensitization including IL-4, IL-5, IL-13 and IL-31RA, however these were not statistically significant (Table 17). One gene, IL-10, showed significantly higher expression in the lung of wildtype mice following OVA challenge, compared to IL-31 transgenic mice.

TABLE 17 mRNA Levels in Total Lung Homogenates from IL-31 Transgenic mice following Sensitization and Challenge with OVA - Comparison of Wildtype versus IL-31 Transgenic ^(a)OVA Challenge ^(a)PBS Gene IL-31 Tg Wildtype IL-31 Tg Wildtype IL-4 0.020 0.041 0.001 0.001 IL-5 0.188 0.300 0.105 0.093 IL-13 0.365 0.645 0.001 0.001 IL-31Ra 0.601 1.023 0.179 0.192 IFNg 0.318 0.324 0.110 0.136 TNFa 0.973 0.654 0.797 0.693 MIP-2 0.946 1.878 1.302 0.539 IL-8R 3.666 4.136 4.205 3.696 CCL27 0.511 0.528 0.806 0.814 Cathepsin L 34.840 43.339 45.421 55.763 Class II 49.180 50.207 24.050 33.128 IL-13Ra2 ND ND ND ND Eotaxin-1 2.267 2.729 0.267 0.182 IL-10 0.033** 0.049 0.009 0.008 CD40 2.559 3.243 2.215 2.714 CD40L 0.747 0.873 0.382 0.494 ^(a)Statistical analysis for differences between groups was performed with one-way ANOVA with Tukey's post-comparison test of all groups (**p < 0.01)

When animals were compared based on OVA versus PBS challenge, the data suggest that wildtype mice are more likely to significantly increase gene levels following OVA challenge compared to IL-31 transgenic animals. Data show that the up-regulation of genes such as IL-4, IL-5, IL-13 and IL-31Ra were more significantly up-regulated in wildtypes OVA sensitized animals compared to PBS sensitized mice than transgenic OVA sensitized compared to transgenic PBS mice. Some genes like Eotaxin and Class II were equally well up-regulated in either the wildtype or IL-31 transgenic OVA sensitized animals compared to their PBS controls (Table 18).

TABLE 18 mRNA Levels in Total Lung Homogenates from IL-31 Transgenic mice following Sensitization and Challenge with OVA - Comparison of OVA versus PBS ^(a)IL-31 Tg ^(a)Wildtype Gene OVA PBS OVA PBS IL-4 0.020 0.001 0.041* 0.001 IL-5 0.188 0.105 0.300* 0.093 IL-13 0.365 0.001 0.645** 0.001 IL-31Ra 0.601 0.179 1.023* 0.192 IFNg 0.318 0.110 0.324 0.136 TNFa 0.973 0.797 0.654 0.693 MIP-2 0.946 1.302 1.878 0.539 IL-8R 3.666 4.205 4.136 3.696 CCL27 0.511*** 0.806 0.528*** 0.814 Cathepsin L 34.840* 45.421 43.339** 55.763 Class II 49.180*** 24.050 50.207** 33.128 IL-13Ra2 ND ND ND ND Eotaxin-1 2.267** 0.267 2.729** 0.182 IL-10 0.033 0.009 0.049** 0.008 CD40 2.559 2.215 3.243 2.714 CD40L 0.747 0.382 0.873 0.494 ^(a)Statistical analysis for differences between groups was performed with one-way ANOVA with Tukey's post-comparison test of all groups (***P < 0.001, **p < 0.01, *p < 0.05)

Analysis of mRNA from BAL cell infiltrates comparing IL-31 transgenic to wildtype controls under conditions of either OVA or PBS intranasal challenge suggests (i) three genes tested, TNFa, IL-8R and Class II, were expressed at significantly different levels in IL-31 transgenics compared to wildtypes in the absence of a antigen-specific challenge. TNFa and Class II were both lower in transgenics versus wildtypes where as IL-8R was expressed at higher levels. (ii) Following OVA intranasal challenge wildtype control mice up-regulated the expression of IL-4, IL-13, IL-8R, Class II, Cathepsin L, Eotaxin, IL-10 and CD40 significantly more than the IL-31 transgenic mice. (iii) IL-31 transgenic mice up-regulated CD40L following OVA challenge significantly more than wildtype littermate controls (Table 19).

TABLE 19 mRNA Levels in BAL mRNA from IL-31 Transgenic and Wildtype mice following Sensitization and Challenge with OVA - Comparison of Wildtype versus IL-31 Transgenic ^(a)OVA ^(a)PBS challenge Gene IL-31 Tg Wildtype IL-31 Tg Wildtype IL-4 0.011*** 0.030 ND ND IL-5 0.071 0.102 0.000 0.001 IL-13 0.028*** 0.044 ND ND IL-31Ra 0.480 0.520 0.010 0.017 IFNg 0.395 0.346 0.025 0.026 TNFa 0.522 0.451 1.924*** 3.316 MIP-2 0.991 1.031 4.960 5.278 IL-8R 0.736*** 1.541 0.767*** 0.350 CCL27 0.176 0.168 0.165 0.200 Cathepsin L 42.517* 55.496 16.574 24.384  Class II 23.420*** 29.767 4.733** 9.228 IL-13Ra2 ND ND ND ND Eotaxin-1 0.001*** 0.005 ND ND IL-10 0.050* 0.066 0.008 0.003 CD40 0.229** 0.265 0.033 0.038 CD40L 0.707** 0.538 0.052 0.075 ^(a)Statistical analysis for differences between groups was performed with one-way ANOVA with Tukey's post-comparison test of all groups (***p < 0.001, **p < 0.01, *p < 0.05)

Data in Table 20 clearly show that OVA intranasal challenge induces a number of genes in both IL-31 transgenic and wildtype OVA treated mice compared to PBS challenge groups. However, two genes, IL-8R and Eotaxin were not up-regulated in IL-31 transgenic OVA challenged mice compared to their PBS controls, whereas both genes were up-regulated in the wildtype mice challenged with OVA, compared to PBS controls (Table 20).

TABLE 20 mRNA Levels in BAL mRNA from IL-31 Transgenic mice following Sensitization and Challenge with OVA - Comparison of OVA versus PBS ^(a)IL-31 Transgenic ^(a)Wildtype Gene OVA PBS OVA PBS IL-4 0.011*** ND 0.030*** ND IL-5 0.071*** 0.000 0.102*** 0.001 IL-13 0.028*** ND 0.044*** ND IL-31Ra 0.480*** 0.010 0.520*** 0.017 IFNg 0.395*** 0.025 0.346*** 0.026 TNFa 0.522*** 1.924 0.451*** 3.316 MIP-2 0.991*** 4.960 1.031*** 5.278 IL-8R 0.736 0.767 1.541*** 0.350 CCL27 0.176 0.165 0.168 0.200 Cathepsin L 42.517*** 16.574  55.496*** 24.384  Class II 23.420*** 4.733 29.767*** 9.228 IL-13Ra2 ND ND ND ND Eotaxin-1 0.001 ND 0.005*** ND IL-10 0.050*** 0.008 0.066*** 0.003 CD40 0.229*** 0.033 0.265*** 0.038 CD40L 0.707*** 0.052 0.538*** 0.075 ^(a)Statistical analysis for differences between groups was performed with one-way ANOVA with Tukey's post-comparison test of all groups (***p < 0.001, **p < 0.01, *p < 0.05)

3.2.4.3.2 BAL Cell Differentials

BAL cell infiltrates were collected and analyzed for cellular content. Although there was a trend towards decreased eosinophil numbers in the lung cell infiltrates of IL-31 Tg animals compared to wildtype control littermates, the data did not reach statistical significance due to variability within the test groups.

3.2.4.3.3 Serum OVA-Specific and Total IgE

Analysis of total IgE in the serum of IL-31 transgenic animals following OVA-sensitization showed significant decreases in the production of total IgE in the circulation of IL-31 transgenic animals compared to littermate wildtype controls (p=0.048, unpaired t test), however there were no statistical differences in the level of OVA-specific IgE detectable in the serum.

3.2.4.4 Summary

Given that IL-31 delivery decreases pulmonary inflammation following allergen sensitization and challenge, we hypothesized that IL-31 transgenic animals would also be less susceptible to allergen induced asthma. Indeed IL-31 transgenics appeared to develop less airway hyper-responsiveness to OVA sensitization and challenge when airway responsiveness was measured by whole body plethysmography. We found that IL-31 transgenics appeared to be more resistant to the up-regulation of Th-2-type genes following OVA sensitization and challenge compared to littermate controls. Moreover, there was a trend towards decreased numbers of eosinophils in the lungs OVA-challenged IL-31 transgenics versus wildtype controls. These data are consistent with our observations that IL-31 over-expression down-regulates pulmonary inflammation.

From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims. 

1. A method of inhibiting, minimizing, reducing, or neutralizing chronic obstructive pulmonary disease (COPD) in a mammal, comprising administering an Interleukin-31 (IL-31) agonist to the mammal wherein pulmonary inflammation is reduced and wherein the IL-31 agonist is administered during sensitization or challenge and wherein the IL-31 agonist comprises amino acid residues 27 to 164 of SEQ ID NO:
 2. 2. The method of claim 1, wherein production of proinflammatory cytokines in the lung and BAL fluid is inhibited, minimized, or neutralized.
 3. The method of claim 2, wherein the proinflammatory cytokines are IL-5 or IL-13.
 4. The method of claim 2, wherein the proinflammatory cytokines are IL-5 and IL-13.
 5. A method of inhibiting, minimizing, reducing, or neutralizing chronic obstructive pulmonary disease (COPD) in a mammal, comprising administering an Interleukin-31 (IL-31) agonist to the mammal wherein pulmonary inflammation is reduced and wherein the IL-31 agonist is administered during sensitization or challenge and wherein the IL-31 agonist has at least 95% sequence identity to the polypeptide comprising the amino acid sequence of SEQ ID NO:2 from residue 27 to
 164. 6. The method of claim 5, wherein the IL-31 agonist is produced in mammalian cells.
 7. The method of claim 5, wherein the IL-31 agonist is produced in E. coli. 